Add Transient annotation to private accessor methods

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

@@ -0,0 +1,126 @@
+/*
+ * 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.Expression;
+import org.openrewrite.java.tree.J;
+import org.openrewrite.java.tree.JavaType;
+import org.openrewrite.java.tree.Statement;
+
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Objects;
+
+@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.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()
+                               && methodReturnsFieldFromClass(method);
+                    }
+
+                    /**
+                     * Check if the given method returns a field defined in the parent class
+                     */
+                    private boolean methodReturnsFieldFromClass(J.MethodDeclaration method) {
+                        J.ClassDeclaration classDecl = getCursor().dropParentUntil(J.ClassDeclaration.class::isInstance).getValue();
+                        // Check if last statement is return
+                        List<Statement> statements = method.getBody().getStatements();
+                        if (statements.isEmpty()) {
+                            return false;
+                        }
+                        Statement lastStatement = statements.get(statements.size() - 1);
+                        if (!(lastStatement instanceof J.Return)) {
+                            return false;
+                        }
+
+                        // Get return value
+                        Expression returnExpr = ((J.Return) lastStatement).getExpression();
+                        if (returnExpr == null) {
+                            return false;
+                        }
+                        final JavaType.Variable returnedVar;
+                        if (returnExpr instanceof J.FieldAccess) { // ie: return this.field;
+                            returnedVar = ((J.FieldAccess) returnExpr).getName().getFieldType();
+                        } else if (returnExpr instanceof J.Identifier) { // ie: return field;
+                            returnedVar = ((J.Identifier) returnExpr).getFieldType();
+                        } else { // instanceof J.Literal (hardcoded value), or something else not a field. ie: return "hello";
+                            return false;
+                        }
+
+                        // Check if return value is a class field
+                        return classDecl.getBody().getStatements().stream()
+                                .filter(J.VariableDeclarations.class::isInstance)
+                                .map(J.VariableDeclarations.class::cast)
+                                .map(J.VariableDeclarations::getVariables)
+                                .flatMap(Collection::stream)
+                                .map(var -> var.getName().getFieldType())
+                                .filter(Objects::nonNull)
+                                .anyMatch(var -> var.equals(returnedVar));
+                    }
+                }
+        );
+    }
+}

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

@@ -22,10 +22,13 @@ tags:
   - javaee7
   - deprecated
 recipeList:
-  - org.openrewrite.java.migrate.javax.AddTableGenerator
   - org.openrewrite.java.migrate.javax.AddColumnAnnotation
   - org.openrewrite.java.migrate.javax.AddDefaultConstructorToEntityClass
+  - org.openrewrite.java.migrate.javax.AddTableGenerator
   - org.openrewrite.java.migrate.javax.AddTransientAnnotationToCollections
+  - org.openrewrite.java.migrate.javax.AddTransientAnnotationToEntity
+  - org.openrewrite.java.migrate.javax.AddTransientAnnotationToPrivateAccessor
   - org.openrewrite.java.migrate.javax.RemoveEmbeddableId
   - org.openrewrite.java.migrate.javax.RemoveTemporalAnnotation
-  - org.openrewrite.java.migrate.javax.UseJoinColumnForMapping
+  - org.openrewrite.java.migrate.javax.UseJoinColumnForMapping
+