This repository contains the project skeleton to implement custom Java rules. It is derived from the base template of the sonar-java project.
- A brief introduction to SonarQube
- Analyzing your first project
- Writing a rule together
- Writing a rule on your own
- Bonus Round
- Additional resources
Start by getting a copy of SonarQube 9.9 Community edition from the SonarQube website.
Unzip the archive, get into the unzipped folder and open a terminal. To start SonarQube, run:
# Linux
./bin/linux-x86-64/sonar.sh console
# Mac OS
./bin/macosx-universal-64/sonar.sh console
# Windows
bin\windows-x86-64\StartSonar.batAfter a few seconds, you should be able to connect to your instance on http://localhost:9000.
Login with the default credentials (user: admin, password: admin) and update with a new password of your choice.
With your new running instance, let's get familiar with some of the concepts in the Sonar ecosystem.
You should be able to list all the rules available to you by browsing on the rules page. You can play around with the filters.
Note how every rule has:
- A unique key
- A description
- A type
- A severity
- A repository of origin
Additionally, a rule may have:
- Multiple language implementations
- Tags
- Customizable parameters
Before moving on, ask yourself:
- How many rules are there for Java?
- Can you find a rule with a customizable parameter?
In order to apply a set of rules to your project, they can be grouped as quality profiles. Sonar provides default a quality profile named "Sonar way". It serves as the default quality profile.
Such a profile can then be:
- copied (an identical separate copy that can be modified)
- extended (depends on the original one that can receive updates but can bring its own modifications)
The new profiles can then be set as defaults for our SonarQube instance or just used for some of our existing projects.
Before moving on, ask yourself:
- How many rules are there in the "Sonar Way" quality profile for Java?
- Is there a difference with the number of available rules?
To get a quick look at your project's health and ensure a reasonable state, Quality Gates can prove useful. It is a combination of a quality profile and a set of conditions that should be matched. The quality gate can either pass (turning green) or fail (turning red). You can leverage this quality gate toggle in your CI pipeline to block releases or trigger alerts for your development team.
Before moving on, ask yourself:
- What is the name of the default quality gate?
- Is this quality gate applied to all code?
We are going to analyze our first project with SonarQube. First, clone or get a copy of the spring-petclinic project. Then follow the instructions to get the project analyzed.
- On the "How do you want to create your project?" Select "Manually".
- Enter "spring-petclinic" as the project name and project key, and click "Set Up"
- Select "Locally",
- On the "Provide a token" step, create the 30-days token and make a copy of it.
- On the "Run analysis on your project" step, select Maven and make a copy of the command suggested by SonarQube
- Before running the command, modify the command:
- replace
mvnwith./mvnwon Linux/Mac - add
-DskipTests=trueto the command (the tests of project are flaky)
- replace
- Open a terminal at the root of the project and run the command to start the analysis
If the command succeeds, your browser tab should update soon with the results of the analysis.
Take some time to look around and explore the results of the analysis.
Before moving on, ask yourself:
- How many issues are detected?
- What is the status of the quality gate?
- What is the version of the project you analyzed?
- How many lines of code are there in the project?
The rules you develop will be delivered using a dedicated, custom plugin, relying on the SonarSource Analyzer for Java API. In order to start working efficiently, we provide a template Maven project that you will fill in while following this tutorial.
This project already contains examples of custom rules. Our goal will be to add a few more!
Every rule starts with a description of sort. It describes the purpose and scope of the rule.
It can sometimes be arbitrary, see the following for example.
“For a method having a single parameter, the types of its return value and its parameter should never be the same.”
We now have an arbitrary but scoped rule specification, let's implement the actual logic.
In this section, we will write a custom rule from scratch. To do so, we will use a Test Driven Development (TDD) approach, relying on writing some test cases first, followed by the implementation of a solution.
Let's first start by describing the rule we want to implement.
When implementing a rule, there is always a minimum of three distinct files to create:
- A test file, which contains Java code used as input data for testing the rule
- A test class, which contains the rule's unit test
- A rule class, which contains the implementation of the rule.
To create our first custom rule (usually called a "check"), let's start by creating these three files in the template project, as described below:
- In folder
/src/test/files, create a new empty file namedReturnTypeDifferentFromSingleParameterSample.java, and copy-paste the content of the following code snippet.
class MyClass {
}- In package
org.sonar.samples.java.checksof/src/test/java, create a new test class calledReturnTypeDifferentFromSingleParameterCheckTestand copy-paste the content of the following code snippet.
package org.sonar.samples.java.checks;
import org.junit.jupiter.api.Test;
class ReturnTypeDifferentFromSingleParameterCheckTest {
@Test
void test() {
}
}- In package
org.sonar.samples.java.checksof/src/main/java, create a new class calledReturnTypeDifferentFromSingleParameterCheckextending classorg.sonar.plugins.java.api.IssuableSubscriptionVisitorprovided by the Java Plugin API. Then, replace the content of thenodesToVisit()method with the content from the following code snippet. This file will be described when dealing with the implementation of the rule!
package org.sonar.samples.java.checks;
import org.sonar.check.Rule;
import org.sonar.plugins.java.api.IssuableSubscriptionVisitor;
import org.sonar.plugins.java.api.tree.Tree.Kind;
import java.util.Collections;
import java.util.List;
@Rule(key = "ReturnTypeDifferentFromSingleParameter")
public class ReturnTypeDifferentFromSingleParameterCheck extends IssuableSubscriptionVisitor {
@Override
public List<Kind> nodesToVisit() {
return Collections.emptyList();
}
}Because we chose a TDD approach, the first thing to do is to write examples of the code our rule will target.
In this file, we consider numerous cases that our rule may encounter during an analysis, and flag the lines which will require our implementation to raise issues.
The flag to be used is a simple // Noncompliant trailing comment on the line of code where an issue should be raised.
Why Noncompliant? Because the flagged lines do not comply with the rule.
Covering all the possible cases is not necessarily required, the goal of this file is to cover all the situations which may be encountered during an analysis, but also to abstract irrelevant details. For instance, in the context of our first rule, the name of a method, the content of its body, and the owner of the method make no difference, whether it's an abstract class, a concrete class, or an interface. Note that this sample file should be structurally correct and all code should compile.
In the test file ReturnTypeDifferentFromSingleParameterSample.java created earlier, copy-paste the following code:
class MyClass {
MyClass(MyClass mc) { }
int foo1() { return 0; }
void foo2(int value) { }
int foo3(int value) { return 0; } // Noncompliant
Object foo4(int value) { return null; }
MyClass foo5(MyClass value) { return null; } // Noncompliant
int foo6(int value, String name) { return 0; }
int foo7(int ... values) { return 0;}
}The test file now contains the following test cases:
- line 2: A constructor, to differentiate the case from a method;
- line 4: A method without parameter (
foo1); - line 5: A method returning void (
foo2); - line 6: A method returning the same type as its parameter (
foo3), which will be noncompliant; - line 7: A method with a single parameter, but a different return type (
foo4); - line 8: Another method with a single parameter and same return type, but with non-primitive types (
foo5), therefore noncompliant too; - line 10: A method with more than 1 parameter (
foo6); - line 11: A method with a variable arity argument (
foo7);
Once the test file is updated, let's update our test class to use it, and link the test to our (not yet implemented) rule.
To do so, get back to our test class ReturnTypeDifferentFromSingleParameterCheckTest, and update the test() method as shown in the following code snippet (you may have to import class org.sonar.java.checks.verifier.CheckVerifier):
@Test
void test() {
CheckVerifier.newVerifier()
.onFile("src/test/files/ReturnTypeDifferentFromSingleParameterSample.java")
.withCheck(new ReturnTypeDifferentFromSingleParameterCheck())
.verifyIssues();
}As you probably noticed, this test class contains a single test, the purpose of which is to verify the behavior of the rule we are going to implement.
To do so, it relies on the usage of the CheckVerifier class, provided by the Java Analyzer rule-testing API.
This CheckVerifier class provides useful methods to validate rule implementations, allowing us to totally abstract all the mechanisms related to analyzer initialization.
Note that while verifying a rule, the verifier will collect lines marked as being Noncompliant, and verify that the rule raises the expected issues and only those issues.
Now, let's proceed to the next step of TDD: make the test fail!
To do so, simply execute the test from the test file using JUnit. The test should fail with the error message "At least one issue expected", as shown in the code snippet below. Since our check is not yet implemented, no issue can be raised yet, so that's the expected behavior.
java.lang.AssertionError: No issue raised. At least one issue expected
at org.sonar.java.checks.verifier.InternalCheckVerifier.assertMultipleIssues(InternalCheckVerifier.java:291)
at org.sonar.java.checks.verifier.InternalCheckVerifier.checkIssues(InternalCheckVerifier.java:231)
at org.sonar.java.checks.verifier.InternalCheckVerifier.verifyAll(InternalCheckVerifier.java:222)
at org.sonar.java.checks.verifier.InternalCheckVerifier.verifyIssues(InternalCheckVerifier.java:167)
at org.sonar.samples.java.checks.ReturnTypeDifferentFromSingleParameterCheckTest.test(ReturnTypeDifferentFromSingleParameterCheckCheckTest.java:13)
...
Before we start with the implementation of the rule itself, you need a little background.
Prior to running any rule, the SonarQube Java Analyzer parses a given Java code file and produces an equivalent data structure: the Syntax Tree.
Each construction of the Java language can be represented with a specific kind of Syntax Tree, detailing each of its particularities.
Each of these constructions is associated with a specific Kind as well as an interface explicitly describing all its particularities.
For instance, the kind associated with the declaration of a method will be org.sonar.plugins.java.api.tree.Tree.Kind.METHOD, and its interface defined by org.sonar.plugins.java.api.tree.MethodTree.
All kinds are listed in the Kind enum of the Java Analyzer API.
When creating the rule class, we chose to implement the IssuableSubscriptionVisitor class from the API.
This class, on top of providing a bunch of useful methods to raise issues, also defines the strategy which will be used when analyzing a file.
As its name is telling us, it is based on a subscription mechanism, allowing to specify on what kind of tree the rule should react.
The list of node types to cover is specified through the nodesToVisit() method.
In the previous steps, we modified the implementation of the method to return an empty list, therefore not subscribing to any node of the syntax tree.
Now it's finally time to jump into the implementation of our first rule!
Go back to the ReturnTypeDifferentFromSingleParameterCheck class, and modify the list of Kinds returned by the nodesToVisit() method.
Since our rule targets method declarations, we only need to visit methods.
To do so, simply make sure that we return a singleton list containing only Kind.METHOD as a parameter of the returned list, as shown in the following code snippet.
@Override
public List<Kind> nodesToVisit() {
return Collections.singletonList(Kind.METHOD);
}Once the nodes to visit are specified, we have to implement how the rule will react when encountering method declarations.
To do so, override method visitNode(Tree tree), inherited from SubscriptionVisitor through IssuableSubscriptionVisitor.
@Override
public void visitNode(Tree tree) {
}Because we registered the rule to visit Method nodes, we know that every time the method is called, the tree parameter will be a org.sonar.plugins.java.api.tree.MethodTree (the interface tree associated with the METHOD kind).
As a first step, we can consequently safely cast the tree directly into a MethodTree, as shown below.
Note that if we had registered multiple node types, we would have to test the node kind before casting by using the method Tree.is(Kind ... kind).
@Override
public void visitNode(Tree tree) {
MethodTree method = (MethodTree) tree;
}Now, let's narrow the focus of the rule by checking that the method has a single parameter, and raise an issue if it's the case.
@Override
public void visitNode(Tree tree) {
MethodTree method = (MethodTree) tree;
if (method.parameters().size() == 1) {
reportIssue(method.simpleName(), "Never do that!");
}
}The method reportIssue(Tree tree, String message) from IssuableSubscriptionVisitor allows reporting an issue on a given tree with a specific message.
In this case, we chose to report the issue at a precise location, which will be the name of the method.
Now, let's test our implementation by executing ReturnTypeDifferentFromSingleParameterCheckCheckTest.test() again.
java.lang.AssertionError: Unexpected at [5, 7, 11]
at org.sonar.java.checks.verifier.InternalCheckVerifier.assertMultipleIssues(InternalCheckVerifier.java:303)
at org.sonar.java.checks.verifier.InternalCheckVerifier.checkIssues(InternalCheckVerifier.java:231)
at org.sonar.java.checks.verifier.InternalCheckVerifier.verifyAll(InternalCheckVerifier.java:222)
at org.sonar.java.checks.verifier.InternalCheckVerifier.verifyIssues(InternalCheckVerifier.java:167)
at org.sonar.samples.java.checks.ReturnTypeDifferentFromSingleParameterCheckCheckTest.test(ReturnTypeDifferentFromSingleParameterCheckCheckTest.java:13)
...
Of course, our test failed again...
The CheckVerifier reported that lines 5, 7, and 11 are raising unexpected issues, as visible in the stack trace above.
By looking back at our test file, it's easy to figure out that raising an issue in line 5 is wrong because the return type of the method is void, line 7 is wrong because Object is not the same as int, and line 11 is also wrong because of the variable arity of the method.
Raising these issues is however correct accordingly to our implementation, as we didn't check for the types of the parameter and return type.
To handle type, however, we will need to rely on more than what we can achieve using only knowledge of the syntax tree.
This time, we will need to use the semantic API!
Question: IssuableSubscriptionVisitor and BaseTreeVisitor
For the implementation of this rule, we chose to use an
IssuableSubscriptionVisitoras the implementation basis of our rule. This visitor offers an easy approach to writing quick and simple rules because it allows us to narrow the focus of our rule to a given set of Kinds to visit by subscribing to them. However, this approach is not always the most optimal one. In such a situation, it could be useful to take a look at another visitor provided with the API:org.sonar.plugins.java.api.tree.BaseTreeVisitor. TheBaseTreeVisitorcontains avisit()method dedicated to each and every kind of syntax tree, and is particularly useful when the visit of a file has to be fine-tuned.In rules already implemented in the Java Plugin, you will be able to find multiple rules using both approaches: An
IssuableSubscriptionVisitoras an entry point, helped by simpleBaseTreeVisitor(s) to identify the pattern in other parts of code.
Up to now, our rule implementation only relied on the data provided directly by the syntax tree that resulted from the parsing of the code. However, the SonarAnalyzer for Java provides a lot more regarding the code being analyzed, because it also constructs a semantic model of the code. This semantic model provides information related to each symbol being manipulated. For a method, for instance, the semantic API will provide useful data such as a method's owner, its usages, the types of its parameters and its return type, the exception it may throw, etc. Don't hesitate to explore the semantic package of the API in order to have an idea of what kind of information you will have access to during analysis!
But now, let's go back to our implementation and take advantage of the semantics.
Once we know that our method has a single parameter, let's start by getting the symbol of the method using the symbol() method from the MethodTree.
@Override
public void visitNode(Tree tree) {
MethodTree method = (MethodTree) tree;
if (method.parameters().size() == 1) {
MethodSymbol symbol = method.symbol();
reportIssue(method.simpleName(), "Never do that!");
}
}From the symbol, it is then pretty easy to retrieve the type of its first parameter, as well as the return type (You may have to import org.sonar.plugins.java.api.semantic.Symbol.MethodSymbol and org.sonar.plugins.java.api.semantic.Type).
@Override
public void visitNode(Tree tree) {
MethodTree method = (MethodTree) tree;
if (method.parameters().size() == 1) {
Symbol.MethodSymbol symbol = method.symbol();
Type firstParameterType = symbol.parameterTypes().get(0);
Type returnType = symbol.returnType().type();
reportIssue(method.simpleName(), "Never do that!");
}
}Since the rule should only raise an issue when these two types are the same, we then simply test if the return type is the same as the type of the first parameter using method is(String fullyQualifiedName), provided through the Type class, before raising the issue.
@Override
public void visitNode(Tree tree) {
MethodTree method = (MethodTree) tree;
if (method.parameters().size() == 1) {
Symbol.MethodSymbol symbol = method.symbol();
Type firstParameterType = symbol.parameterTypes().get(0);
Type returnType = symbol.returnType().type();
if (returnType.is(firstParameterType.fullyQualifiedName())) {
reportIssue(method.simpleName(), "Never do that!");
}
}
}Now, execute the test class again.
Test passed? If not, then check if you somehow missed a step.
If it passed...
🎉 Congratulations! 🎊
You implemented your first custom rule for the SonarQube Java Analyzer!
When writing custom Java rules, you can only use classes from package org.sonar.plugins.java.api.
When browsing the existing 600+ rules from the SonarSource Analyzer for Java, you will sometime notice the use of some other utility classes, is not part of the API. While these classes could be sometime extremely useful in your context, these classes are not available at runtime for custom rule plugins. It means that, while your unit tests are still going to pass when building your plugin, your rules will most likely make analysis crash at analysis time.
OK, you are probably quite happy at this point, as our first rule is running as expected... However, we are not really done yet. Before playing our rule against any real projects, we have to finalize its creation within the custom plugin, by registering it.
For this workshop, the license on the source files does not matter. However, there is a check for it in the build steps that we did not have the time to remove. To apply the license from the command line, you can run:
./mvnw license:formatWith this, you should be able to start registering the new rule.
The first thing to do is to provide our rule with all the metadata which will allow us to register it properly in the SonarQube platform. There are two ways to add metadata for your rule:
- annotation
- static documentation
While annotation provides a handy way to document the rule, static documentation offers the possibility for richer information. Incidentally, static documentation is also the way rules in the sonar-java analyzer are described.
To provide metadata for your rule, you need to create an HTML file, where you can provide an extended textual description of the rule, and a JSON file, with the actual metadata.
In the case of ReturnTypeDifferentFromSingleParameter, you will head to the src/main/resources/org/sonar/l10n/java/rules/java/ folder to create ReturnTypeDifferentFromSingleParameter.html and ReturnTypeDifferentFromSingleParameter.json.
We first need to populate the HTML file with some information that will help developers fix the issue.
<p>For a method having a single parameter, the types of its return value and its parameter should never be the same.</p>
<h2>Noncompliant Code Example</h2>
<pre>
class MyClass {
int doSomething(int a) { // Noncompliant
return 42;
}
}
</pre>
<h2>Compliant Solution</h2>
<pre>
class MyClass {
int doSomething() { // Compliant
return 42;
}
long doSomething(int a) { // Compliant
return 42L;
}
}
</pre>We can now add metadata to src/main/resources/org/sonar/l10n/java/rules/java/ReturnTypeDifferentFromSingleParameter.json:
{
"title": "Return type and parameter of a method should not be the same",
"type": "Bug",
"status": "ready",
"tags": [
"bugs"
],
"defaultSeverity": "Critical"
}With this example, we have a concise but descriptive title for our rule, the type of an issue it highlights, its status (ready or deprecated), the tags that should bring it up in a search, and the severity of the issue.
The second thing to do is to activate the rule within the plugin.
To do so, open the class RulesList (org.sonar.samples.java.RulesList).
In this class, you will notice methods getJavaChecks() and getJavaTestChecks().
These methods are used to register our rules alongside the rule of the Java plugin.
Note that rules registered in getJavaChecks() will only be played against source files, while rules registered in getJavaTestChecks() will only be played against test files.
To register the rule, simply add the rule class to the list builder, as in the following code snippet:
public static List<Class<? extends JavaCheck>> getJavaChecks() {
return Collections.unmodifiableList(Arrays.asList(
// other rules...
ReturnTypeDifferentFromSingleParameterCheck.class
));
}Because your rules are relying on the SonarSource Analyzer for Java API, you also need to tell the parent Java plugin that some new rules have to be retrieved.
If you are using the template custom plugin as a base of this tutorial, you should have everything done already, but feel free to have a look at the MyJavaFileCheckRegistrar.java class, which connects the dots.
Finally, be sure that this registrar class is also correctly added as an extension for your custom plugin, by adding it to your Plugin definition class (MyJavaRulesPlugin.java).
/**
* Provide the "checks" (implementations of rules) classes that are going to be executed during
* source code analysis.
*
* This class is a batch extension by implementing the {@link org.sonar.plugins.java.api.CheckRegistrar} interface.
*/
@SonarLintSide
public class MyJavaFileCheckRegistrar implements CheckRegistrar {
/**
* Register the classes that will be used to instantiate checks during analysis.
*/
@Override
public void register(RegistrarContext registrarContext) {
// Call to registerClassesForRepository to associate the classes with the correct repository key
registrarContext.registerClassesForRepository(MyJavaRulesDefinition.REPOSITORY_KEY, checkClasses(), testCheckClasses());
}
/**
* Lists all the main checks provided by the plugin
*/
public static List<Class<? extends JavaCheck>> checkClasses() {
return RulesList.getJavaChecks();
}
/**
* Lists all the test checks provided by the plugin
*/
public static List<Class<? extends JavaCheck>> testCheckClasses() {
return RulesList.getJavaTestChecks();
}
}Now, because we added a new rule, we also need to update our tests to make sure it is taken into account.
To do so, navigate to its corresponding test class, named MyJavaFileCheckRegistrarTest, and update the expected number of rules from 8 to 9.
class MyJavaFileCheckRegistrarTest {
@Test
void checkNumberRules() {
CheckRegistrar.RegistrarContext context = new CheckRegistrar.RegistrarContext();
MyJavaFileCheckRegistrar registrar = new MyJavaFileCheckRegistrar();
registrar.register(context);
assertThat(context.checkClasses()).hasSize(8); // change it to 9, we added a new one!
assertThat(context.testCheckClasses()).isEmpty();
}
}At this point, we've completed the implementation of the first custom rule and registered it into the custom plugin. The last remaining step is to test it directly with the SonarQube platform and try to analyze a project!
Start by building the project using Maven.
$ ./mvnw clean verify
[INFO] Scanning for projects...
[INFO]
[INFO] -------------< org.sonar.samples.java:epfl-sonar-workshop >-------------
[INFO] Building EPFL Sonar Workshop 7.16.0.30901
[INFO] from pom.xml
[INFO] ----------------------------[ sonar-plugin ]----------------------------
...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 8.762 s
[INFO] Finished at: 2021-03-02T12:17:28+01:00
[INFO] ------------------------------------------------------------------------
Then, grab the jar file epfl-sonar-workshop-7.16.0.30901.jar from the target folder of the project, and move it to the extensions folder of your SonarQube instance, which will be located at $SONAR_HOME/extensions/plugins.
Now, (re-)start your SonarQube instance, log in as admin, and navigate to the Rules tab.
From there, under the language section, select "Java", and then "Rules for the EPFL workshop" under the repository section. Your rule should now be visible (with all the other sample rules).
Enable the rule by going back to quality profiles and extending the Java "Sonar way" profile (name with something you will recognize). Set the new quality profile as default by clicking on the Gear icon at the top right and then clicking "Set as default". Select the "Activate More" option and find your rule using the search bar. Select your rule and click "Activate".
Once activated (not sure how? see quality-profiles), the only step remaining is to analyze one of your projects!
When encountering a method returning the same type as its parameter, the custom rule will now raise an issue, as visible in the following picture:
Following the methodology in the previous section, write a rule based on the following specification.
A method's return type should narrow down to match the type of the values returned
<p>A method's return type should narrow down to match the potential value it matches</p>
<p>Using a more specific type helps the caller to check the return value.</p>
<h2>Noncompliant Code Example</h2>
<pre>
class MyClass {
Object f(boolean cond) { // Noncompliant
if (cond) {
return "b";
}
return "a";
}
}
</pre>
<h2>Compliant Solution</h2>
<pre>
class MyClass {
String f(boolean cond) { // Compliant
if (cond) {
return "b";
}
return "a";
}
}
</pre>Make sure to add test cases in your sample file where the rule is not supposed to raise.
Hint: Take a look at NoIfStatementInTestsRule
Write a rule based on the following description.
Getters that return collections should return unmodifiable collections
You have to add a @RuleProperty to your Rule.
Check this example: SecurityAnnotationMandatoryRule.java
In the pom.xml, define in the Maven Dependency Plugin part all the JARs you need to run your Unit Tests.
For example, if your sample code used in your Unit Tests is having a dependency on Spring, add it there.
See: pom.xml#L137-L197
You can raise an issue on a given line, but you can also raise it at a specific Token. Because of that, you may want to specify, in your sample code used by your Unit Tests, the exact location, i.e. in between which 2 specific Columns, where you are expecting the issue to be raised.
This can be achieved using the special keywords sc (start-column) and ec (end-column) in the // Noncompliant comment.
In the following example, we are expecting to have the issue being raised between the columns 27 and 32 (i.e. exactly on the "Order" variable type):
public String updateOrder(Order order){ // Noncompliant [[sc=27;ec=32]] {{Don't use Order here because it's an @Entity}}
// ...
}Starting from Java Plugin API 3.7 (October 2015), the Java source version can be accessed directly when writing custom rules.
This can be achieved by simply calling the method getJavaVersion() from the context.
Note that the method will return null only when the property is not set.
Similarly, it is possible to specify to the verifier a version of Java to be considered as runtime execution, calling method verify(String filename, JavaFileScanner check, int javaVersion).
@Beta
public interface JavaFileScannerContext {
// ...
@Nullable
Integer getJavaVersion();
}All contents under this directory are licensed under the more permissive MIT No Attribution license.