From 038637c14a864af5132ed84cff924d73c277f5e0 Mon Sep 17 00:00:00 2001
From: Holger Partsch <holger.partsch@sap.com>
Date: Wed, 1 May 2024 15:42:33 +0200
Subject: [PATCH] try to rewrite method references

---
 .../migrate/lombok/LombokValueToRecord.java   | 22 ++++++
 .../lombok/LombokValueToRecordTest.java       | 72 +++++++++++++++++++
 2 files changed, 94 insertions(+)

diff --git a/src/main/java/org/openrewrite/java/migrate/lombok/LombokValueToRecord.java b/src/main/java/org/openrewrite/java/migrate/lombok/LombokValueToRecord.java
index 7e734eedab..9509385f9d 100644
--- a/src/main/java/org/openrewrite/java/migrate/lombok/LombokValueToRecord.java
+++ b/src/main/java/org/openrewrite/java/migrate/lombok/LombokValueToRecord.java
@@ -236,6 +236,28 @@ public J.MethodInvocation visitMethodInvocation(J.MethodInvocation method, Execu
                     );
         }
 
+        @Override
+        public J.MemberReference visitMemberReference(J.MemberReference memberReference, ExecutionContext ctx) {
+            // when "memberReference" is "a::getTest"
+            // memberReference.getMethodType() == null
+            JavaType.Method methodType = memberReference.getMethodType();
+            if(methodType == null) {
+                return memberReference;
+            }
+
+            JavaType.FullyQualified declaringType = methodType.getDeclaringType();
+            String methodName = methodType.getName();
+            String classFqn = declaringType.getFullyQualifiedName();
+            if(recordTypeToMembers.containsKey(classFqn)
+                    && recordTypeToMembers.get(classFqn).contains(getterMethodNameToFluentMethodName(methodName))
+                    && methodName.startsWith(STANDARD_GETTER_PREFIX)) {
+                return memberReference.withMethodType(methodType.withName(getterMethodNameToFluentMethodName(methodName)));
+            }
+
+            return memberReference;
+        }
+
+
         private boolean isMethodInvocationOnRecordTypeClassMember(J.MethodInvocation methodInvocation) {
             Expression expression = methodInvocation.getSelect();
             if (!isClassExpression(expression)) {
diff --git a/src/test/java/org/openrewrite/java/migrate/lombok/LombokValueToRecordTest.java b/src/test/java/org/openrewrite/java/migrate/lombok/LombokValueToRecordTest.java
index d0ebcd4e6e..7de608b393 100644
--- a/src/test/java/org/openrewrite/java/migrate/lombok/LombokValueToRecordTest.java
+++ b/src/test/java/org/openrewrite/java/migrate/lombok/LombokValueToRecordTest.java
@@ -24,6 +24,8 @@
 import org.openrewrite.test.RewriteTest;
 import org.openrewrite.test.TypeValidation;
 
+import java.util.function.Supplier;
+
 import static org.openrewrite.java.Assertions.*;
 
 class LombokValueToRecordTest implements RewriteTest {
@@ -243,6 +245,76 @@ public record A(
         );
     }
 
+    public static class A  {
+        String test;
+
+        public String getTest() {
+            return test;
+        }
+    }
+    @Test
+    @Issue("https://github.com/openrewrite/rewrite-migrate-java/issues/449")
+    void methodReferences() {
+
+        var a = new A();
+
+        //language=java
+        rewriteRun(
+          s -> s.typeValidationOptions(TypeValidation.none()),
+          java(
+            """
+              package example;
+              
+              import lombok.Value;
+              import java.util.function.Supplier;
+              
+              @Value
+              public class A {
+                String test;
+                
+              }
+              
+              class B {
+              
+              
+                public static String classMethod() {
+                    return "foo";
+                }
+              
+              }
+              
+              class Using {
+                
+                 Supplier<String> usingMethodReference() {
+                    A a = new A("foo");
+                    return a::getTest;
+                }
+              
+              }
+              """,
+            """
+              package example;
+              
+              import java.util.function.Supplier;
+               
+              public record A(
+                String test) {
+              }
+              
+              class Using {
+                
+                 Supplier<String> usingMethodReference() {
+                    A a = new A("foo");
+                    return a::test;
+                }
+              
+              }
+              """
+          )
+        );
+
+    }
+
     @Nested
     class Unchanged {
         @Test