Each element should return a map instead of JSON string where possible

to make accessing the JSON easier in MVEL elements.
No two elements should have two names.

yard-core/src/main/java/org/kie/yard/core/DTableUnitBuilder.java

@@ -85,13 +85,14 @@ private OnExecute getExecutionAction(String hitPolicy) {
         if (hitPolicy == null || Objects.equals("ANY", hitPolicy)) {
             return (ruleDefinition, storeHandle) -> {
                 final RuleCell rc = parseGenericRuleThen(ruleDefinition);
-                storeHandle.set(rc.value);
+                Object value = resolveValue(rc.value);
+                storeHandle.set(value);
             };
         } else if (Objects.equals("FIRST", hitPolicy)) {
             return (ruleDefinition, storeHandle) -> {
                 if (!storeHandle.isValuePresent()) {
                     final RuleCell rc = parseGenericRuleThen(ruleDefinition);
-                    storeHandle.set(rc.value);
+                    storeHandle.set(resolveValue(rc.value));
                 }
             };
         } else if (Objects.equals("COLLECT", hitPolicy)) {
@@ -102,22 +103,22 @@ private OnExecute getExecutionAction(String hitPolicy) {
                 final RuleCell rc = parseGenericRuleThen(ruleDefinition);
 
                 if (storeHandle.get() instanceof List list) {
-                    list.add(resolveValue(rc));
+                    list.add(resolveValue(rc.value));
                 }
             };
         } else {
             throw new UnsupportedOperationException("Not implemented ");
         }
     }
 
-    private Object resolveValue(final RuleCell rc) {
+    private Object resolveValue(Object value) {
         try {
-            if (rc.value instanceof String text) {
+            if (value instanceof String text) {
                 return jsonMapper.readValue(text, Map.class);
             }
         } catch (JsonProcessingException ignored) {
         }
-        return rc.value;
+        return value;
     }
 
     private RuleCell parseGenericRuleThen(Rule rule) {

yard-core/src/main/java/org/kie/yard/core/JShellLiteralExpressionInterpreter.java

@@ -18,10 +18,16 @@
  */
 package org.kie.yard.core;
 
-import javax.script.*;
 import java.util.Map;
 import java.util.Map.Entry;
 
+import javax.script.Bindings;
+import javax.script.Compilable;
+import javax.script.CompiledScript;
+import javax.script.ScriptEngine;
+import javax.script.ScriptEngineManager;
+import javax.script.ScriptException;
+
 public class JShellLiteralExpressionInterpreter implements Firable {
 
     private final String name;

yard-core/src/main/java/org/kie/yard/core/MVELLiteralExpressionInterpreter.java

@@ -1,5 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
 package org.kie.yard.core;
 
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.json.JsonMapper;
 import org.mvel2.MVEL;
 
 import java.util.HashMap;
@@ -9,6 +29,8 @@ public class MVELLiteralExpressionInterpreter implements Firable {
     private final String name;
     private final QuotedExprParsed expr;
 
+    private final JsonMapper jsonMapper = JsonMapper.builder().build();
+
     public MVELLiteralExpressionInterpreter(final String name,
                                             final QuotedExprParsed expr) {
         this.name = name;
@@ -31,11 +53,20 @@ public int fire(final Map<String, Object> context,
         try {
             String rewrittenExpression = expr.getRewrittenExpression();
             final Object result = MVEL.eval(rewrittenExpression, internalContext);
-            units.outputs().get(name).set(result);
+            units.outputs().get(name).set(resolveValue(result));
             return 1;
         } catch (Exception e) {
             throw new RuntimeException("interpretation failed at runtime", e);
-            // TODO why throw and not return 0?
         }
     }
+
+    private Object resolveValue(Object value) {
+        try {
+            if (value instanceof String text) {
+                return jsonMapper.readValue(text, Map.class);
+            }
+        } catch (JsonProcessingException ignored) {
+        }
+        return value;
+    }
 }

yard-core/src/main/java/org/kie/yard/core/YaRDParser.java

@@ -23,7 +23,6 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
-import java.util.Objects;
 
 import org.drools.ruleunits.api.DataSource;
 import org.kie.yard.api.model.DecisionLogic;
@@ -71,8 +70,8 @@ private String read(Reader reader) throws Exception {
         int numRead;
         while ((numRead = reader.read(buf)) != -1) {
             String readData = String.valueOf(buf,
-                                             0,
-                                             numRead);
+                    0,
+                    numRead);
             fileData.append(readData);
             buf = new char[1024];
         }
@@ -92,10 +91,16 @@ private YaRDDefinitions parse(String yaml) throws IOException {
     }
 
     private void appendUnits(List<Element> list) {
+        final List<String> existingNames = new ArrayList<>();
         for (Element hi : list) {
-            String nameString = hi.getName();
+            final String nameString = hi.getName();
+            if (existingNames.contains(nameString)) {
+                throw new IllegalArgumentException("Two element definitions with the same name are not allowed.");
+            } else {
+                existingNames.add(nameString);
+            }
             LOG.debug("parsing {}", nameString);
-            Firable decisionLogic = createDecisionLogic(nameString, hi.getLogic());
+            final Firable decisionLogic = createDecisionLogic(nameString, hi.getLogic());
             definitions.units().add(decisionLogic);
         }
     }

yard-core/src/main/java/org/kie/yard/core/YaRDRunner.java

@@ -25,22 +25,22 @@
 
 public class YaRDRunner {
 
-    private final YaRDDefinitions units;
+    private final YaRDDefinitions definitions;
     private final JsonMapper jsonMapper = JsonMapper.builder().build();
     private final String name;
 
     public YaRDRunner(final String yaml) throws IOException {
         final YaRDParser parser = new YaRDParser(yaml);
         name = parser.getModel().getName();
-        units = parser.getDefinitions();
+        definitions = parser.getDefinitions();
     }
 
     public String getName() {
         return name;
     }
 
     public Map<String, Object> evaluate(final Map<String, Object> map) {
-        return units.evaluate(map);
+        return definitions.evaluate(map);
     }
 
     public String evaluate(String jsonInputCxt) throws Exception {

yard-core/src/test/java/org/kie/yard/core/DomesticPackagePricesTest.java

@@ -20,10 +20,9 @@
 
 import java.util.Map;
 
-import com.fasterxml.jackson.databind.json.JsonMapper;
 import org.junit.jupiter.api.Test;
 
-import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class DomesticPackagePricesTest
         extends TestBase {
@@ -41,7 +40,8 @@ public void testMPackage() throws Exception {
                 }
                 """;
         Map<String, Object> outputJSONasMap = evaluate(CTX, FILE_NAME);
-        assertThat(outputJSONasMap).hasFieldOrPropertyWithValue("Package", "{ \"Size\": \"M\", \"Cost\": 6.90 }");
+        assertEquals(6.9, ((Map) outputJSONasMap.get("Package")).get("Cost"));
+        assertEquals("M", ((Map) outputJSONasMap.get("Package")).get("Size"));
     }
 
     @Test
@@ -55,6 +55,7 @@ public void testLPackage() throws Exception {
                 }
                 """;
         Map<String, Object> outputJSONasMap = evaluate(CTX, FILE_NAME);
-        assertThat(outputJSONasMap).hasFieldOrPropertyWithValue("Package", "{ \"Size\": \"L\", \"Cost\": 8.90 }");
+        assertEquals(8.9, ((Map) outputJSONasMap.get("Package")).get("Cost"));
+        assertEquals("L", ((Map) outputJSONasMap.get("Package")).get("Size"));
     }
 }

yard-core/src/test/java/org/kie/yard/core/DublicateElementNameTest.java

@@ -0,0 +1,41 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.kie.yard.core;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class DublicateElementNameTest
+        extends TestBase {
+
+    private static final String FILE_NAME = "/two-elements-with-duplicate-name.yml";
+
+    @Test
+    public void testNoDublicateNames() throws Exception {
+        final String CTX = """
+                {
+                    "Age": 10
+                }
+                """;
+        assertThrows(IllegalArgumentException.class, () ->
+                evaluate(CTX, FILE_NAME)
+        );
+    }
+}

yard-core/src/test/java/org/kie/yard/core/MVELJSONTest.java

@@ -0,0 +1,59 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.kie.yard.core;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class MVELJSONTest
+        extends TestBase {
+
+    private static final String FILE_NAME = "/mvel-json-dot-access.yml";
+
+    @Test
+    public void testMVELManagesJSONMaps() throws Exception {
+        final String CTX = """
+                {
+                    "Work Address":true
+                }
+                """;
+        final Map<String, Object> output = evaluate(CTX, FILE_NAME);
+
+        final Map mailingAddress = (Map) output.get("Mailing Address");
+        assertEquals("Work Street", mailingAddress.get("Street"));
+        assertEquals(23, mailingAddress.get("Number"));
+
+        final List deliveryItemNames = (List) output.get("Delivery Item Names");
+        assertEquals(3, deliveryItemNames.size());
+        assertTrue(deliveryItemNames.contains("Work Shoes"));
+        assertTrue(deliveryItemNames.contains("Work Hat"));
+        assertTrue(deliveryItemNames.contains("Work Shirt"));
+
+        final Map JSONTest= (Map) output.get("JSON Test");
+        assertEquals("Best Company LTD", JSONTest.get("Company"));
+
+        final Map mapTest = (Map) output.get("Map Test");
+        assertEquals("Hello", mapTest.get("Map"));
+    }
+}