Add Transient annotation to private accessor methods

src/main/java/org/openrewrite/java/migrate/javax/AddTransientAnnotationToPrivateAccessor.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * Licensed 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.openrewrite.java.migrate.javax;
+
+import lombok.EqualsAndHashCode;
+import lombok.Value;
+import org.openrewrite.ExecutionContext;
+import org.openrewrite.Preconditions;
+import org.openrewrite.Recipe;
+import org.openrewrite.TreeVisitor;
+import org.openrewrite.java.JavaIsoVisitor;
+import org.openrewrite.java.JavaParser;
+import org.openrewrite.java.JavaTemplate;
+import org.openrewrite.java.search.FindAnnotations;
+import org.openrewrite.java.search.UsesType;
+import org.openrewrite.java.tree.J;
+import org.openrewrite.java.tree.JavaType;
+
+import java.util.Comparator;
+
+@Value
+@EqualsAndHashCode(callSuper = false)
+public class AddTransientAnnotationToPrivateAccessor extends Recipe {
+
+    @Override
+    public String getDisplayName() {
+        return "Private accessor methods must have a `@Transient` annotation";
+    }
+
+    @Override
+    public String getDescription() {
+        return "According to the JPA 2.1 specification, when property access is used, the property accessor methods " +
+               "must be public or protected. OpenJPA ignores any private accessor methods, whereas EclipseLink persists " +
+               "those attributes. To ignore private accessor methods in EclipseLink, the methods must have a " +
+               "`@Transient` annotation.";
+    }
+
+
+    @Override
+    public TreeVisitor<?, ExecutionContext> getVisitor() {
+        return Preconditions.check(
+                new UsesType<>("javax.persistence.Entity", true),
+                new JavaIsoVisitor<ExecutionContext>() {
+                    @Override
+                    public J.ClassDeclaration visitClassDeclaration(J.ClassDeclaration classDecl, ExecutionContext ctx) {
+                        if (!FindAnnotations.find(classDecl, "javax.persistence.Entity").isEmpty()){
+                            return super.visitClassDeclaration(classDecl, ctx);
+                        }
+                        // Exit if parent class is not tagged for JPA
+                        return classDecl;
+                    }
+
+                    @Override
+                    public J.MethodDeclaration visitMethodDeclaration(J.MethodDeclaration md, ExecutionContext ctx) {
+                        if (isPrivateAccessorMethodWithoutTransientAnnotation(md)) {// Add @Transient annotation
+                            maybeAddImport("javax.persistence.Transient");
+                            return JavaTemplate.builder("@Transient")
+                                    .contextSensitive()
+                                    .javaParser(JavaParser.fromJavaVersion().classpathFromResources(ctx, "javax.persistence-api-2.2"))
+                                    .imports("javax.persistence.Transient")
+                                    .build()
+                                    .apply(getCursor(), md.getCoordinates().addAnnotation(Comparator.comparing(J.Annotation::getSimpleName)));
+                        }
+                        return md;
+                    }
+
+                    private boolean isPrivateAccessorMethodWithoutTransientAnnotation(J.MethodDeclaration method) {
+                        return method.hasModifier(J.Modifier.Type.Private)
+                               && method.getParameters().get(0) instanceof J.Empty
+                               && method.getReturnTypeExpression().getType() != JavaType.Primitive.Void
+                               && FindAnnotations.find(method, "javax.persistence.Transient").isEmpty()
+                               && method.getBody().getStatements().get(0) instanceof J.Return
+                               && methodReturnsFieldFromClass((J.Return) method.getBody().getStatements().get(0));
+                    }
+
+                    /**
+                     * Check if the given method returns a field defined in the given class
+                     */
+                    private boolean methodReturnsFieldFromClass(J.Return returnStatement) {
+                        J.ClassDeclaration classDecl = getCursor().dropParentUntil(parent -> parent instanceof J.ClassDeclaration).getValue();
+                        JavaType.Variable returnedVar = ((J.Identifier)returnStatement.getExpression()).getFieldType();
+                        return classDecl.getBody().getStatements().stream()
+                                .filter(statement -> statement instanceof J.VariableDeclarations)
+                                .map(J.VariableDeclarations.class::cast)
+                                .map(J.VariableDeclarations::getVariables)
+                                .flatMap(vars -> vars.stream())
+                                .map(var -> var.getName().getFieldType())
+                                .anyMatch(var -> var.equals(returnedVar));
+                    }
+                }
+        );
+    }
+}

src/main/resources/META-INF/rewrite/openjpa-to-eclipselink.yml

@@ -22,4 +22,5 @@ tags:
   - javaee7
   - deprecated
 recipeList:
-  - org.openrewrite.java.migrate.javax.AddTableGenerator
+  - org.openrewrite.java.migrate.javax.AddTableGenerator
+  - org.openrewrite.java.migrate.javax.AddTransientAnnotationToPrivateAccessor

src/test/java/org/openrewrite/java/migrate/javax/AddTransientAnnotationToPrivateAccessorTest.java

@@ -0,0 +1,201 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * Licensed 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.openrewrite.java.migrate.javax;
+
+import org.junit.jupiter.api.Test;
+import org.openrewrite.DocumentExample;
+import org.openrewrite.InMemoryExecutionContext;
+import org.openrewrite.java.JavaParser;
+import org.openrewrite.test.RecipeSpec;
+import org.openrewrite.test.RewriteTest;
+
+import static org.openrewrite.java.Assertions.java;
+
+class AddTransientAnnotationToPrivateAccessorTest implements RewriteTest {
+    @Override
+    public void defaults(RecipeSpec spec) {
+        spec.parser(JavaParser.fromJavaVersion().classpathFromResources(new InMemoryExecutionContext(), "javax.persistence-api-2.2"))
+          .recipe(new AddTransientAnnotationToPrivateAccessor());
+    }
+
+    @DocumentExample
+    @Test
+    void addTransientToMethodReturningIdentifier() {
+        //language=java
+        rewriteRun(
+          java(
+            """
+              package entities;
+
+              import javax.persistence.Entity;
+              import javax.persistence.Id;
+
+              @Entity
+              public class PrivateAccessor  {
+                  private int id;
+                  private int nonPersistentField;
+
+                  @Id
+                  public int getId() {
+                      return id;
+                  }
+
+                  private int getNonPersistentField() {
+                      return nonPersistentField;
+                  }
+              }
+              """,
+            """
+              package entities;
+
+              import javax.persistence.Entity;
+              import javax.persistence.Id;
+              import javax.persistence.Transient;
+
+              @Entity
+              public class PrivateAccessor  {
+                  private int id;
+                  private int nonPersistentField;
+
+                  @Id
+                  public int getId() {
+                      return id;
+                  }
+
+                  @Transient
+                  private int getNonPersistentField() {
+                      return nonPersistentField;
+                  }
+              }
+              """
+          )
+        );
+    }
+
+    @Test
+    void addTransientToMethodReturningFieldAccess() {
+        //language=java
+        rewriteRun(
+          java(
+            """
+              package entities;
+
+              import javax.persistence.Entity;
+              import javax.persistence.Id;
+
+              @Entity
+              public class PrivateAccessor  {
+                  private int id;
+                  private int nonPersistentField;
+
+                  @Id
+                  public int getId() {
+                      return id;
+                  }
+
+                  private int getNonPersistentField() {
+                      return this.nonPersistentField;
+                  }
+              }
+              """,
+            """
+              package entities;
+
+              import javax.persistence.Entity;
+              import javax.persistence.Id;
+              import javax.persistence.Transient;
+
+              @Entity
+              public class PrivateAccessor  {
+                  private int id;
+                  private int nonPersistentField;
+
+                  @Id
+                  public int getId() {
+                      return id;
+                  }
+
+                  @Transient
+                  private int getNonPersistentField() {
+                      return this.nonPersistentField;
+                  }
+              }
+              """
+          )
+        );
+    }
+
+    @Test
+    void doNotChangePublicGetter() {
+        //language=java
+        rewriteRun(
+          java(
+            """
+              package entities;
+
+              import javax.persistence.Entity;
+              import javax.persistence.Id;
+
+              @Entity
+              public class PrivateAccessor  {
+                private int id;
+                private int field;
+
+                @Id
+                public int getId() {
+                  return id;
+                }
+
+                public int getField() {
+                  return field; // Public method
+                }
+              }
+              """
+          )
+        );
+    }
+
+
+    @Test
+    void doNotChangeVoidReturnType() {
+        //language=java
+        rewriteRun(
+          java(
+            """
+              package entities;
+
+              import javax.persistence.Entity;
+              import javax.persistence.Id;
+
+              @Entity
+              public class PrivateAccessor  {
+                  private int id;
+                  private int field;
+
+                  @Id
+                  public int getId() {
+                    return id;
+                  }
+
+                  private void getField() {
+                    // void return type
+                  }
+              }
+              """
+          )
+        );
+    }
+}