Merge pull request #1354 from adangel/issue-1352

[java] MissingSerialVersionUID false-negative with abstract classes

docs/pages/release_notes.md

@@ -63,6 +63,13 @@ until the next major release but it is recommended to stop using them.
 `.internal` packages or hidden will be tagged `@InternalApi` before that major release, and
 the breaking API changes will be performed in 7.0.0.
 
+#### Modified Rules
+
+*   The rule {% rule java/errorprone/MissingSerialVersionUID %} (`java-errorprone`) has been modified
+    in order to recognize also missing `serialVersionUID` fields in abstract classes, if they are serializable.
+    Each individual class in the inheritance chain needs an own serialVersionUID field. See also [Should an abstract class have a serialVersionUID](https://stackoverflow.com/questions/893259/should-an-abstract-class-have-a-serialversionuid).
+    This change might lead to additional violations in existing code bases.
+
 ### Fixed Issues
 
 *   apex-bestpractices
@@ -72,6 +79,7 @@ the breaking API changes will be performed in 7.0.0.
     *   [#1334](https://github.com/pmd/pmd/issues/1334): \[java] LinguisticNaming should support AtomicBooleans
 *   java-errorprone
     *   [#1350](https://github.com/pmd/pmd/issues/1350): \[java] MissingSerialVersionUID false-positive on interfaces
+    *   [#1352](https://github.com/pmd/pmd/issues/1352): \[java] MissingSerialVersionUID false-negative with abstract classes
 *   java-performance
     *   [#1325](https://github.com/pmd/pmd/issues/1325): \[java] False positive in ConsecutiveLiteralAppends
 

pmd-java/src/main/resources/category/java/errorprone.xml

@@ -2294,6 +2294,8 @@ public void bar(int status) {
           externalInfoUrl="${pmd.website.baseurl}/pmd_rules_java_errorprone.html#missingserialversionuid">
         <description>
 Serializable classes should provide a serialVersionUID field.
+The serialVersionUID field is also needed for abstract base classes. Each individual class in the inheritance
+chain needs an own serialVersionUID field. See also [Should an abstract class have a serialVersionUID](https://stackoverflow.com/questions/893259/should-an-abstract-class-have-a-serialversionuid).
         </description>
         <priority>3</priority>
         <properties>
@@ -2301,7 +2303,6 @@ Serializable classes should provide a serialVersionUID field.
                 <value>
 <![CDATA[
 //ClassOrInterfaceDeclaration
-    [@Abstract = 'false']
     [@Interface = 'false']
     [count(ClassOrInterfaceBody/ClassOrInterfaceBodyDeclaration
         /FieldDeclaration/VariableDeclarator/VariableDeclaratorId[@Image='serialVersionUID']) = 0]

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/errorprone/xml/MissingSerialVersionUID.xml

@@ -67,16 +67,24 @@ public interface Foo implements Bar{
      ]]></code>
     </test-code>
     <test-code>
-        <description><![CDATA[
-abstract case
-     ]]></description>
-        <expected-problems>0</expected-problems>
+        <description>abstract case, see #1352</description>
+        <expected-problems>1</expected-problems>
         <code><![CDATA[
 import java.io.Serializable;
 public abstract class Foo implements Serializable {
 }
      ]]></code>
     </test-code>
+    <test-code>
+        <description>inherited abstract case</description>
+        <expected-problems>1</expected-problems>
+        <code><![CDATA[
+package net.sourceforge.pmd.lang.java.rule.errorprone;
+public abstract class AbstractMissingSerialVersionUIDTest extends MissingSerialVersionUIDBase {
+    // no serial version UID
+}
+        ]]></code>
+    </test-code>
     <test-code>
         <description><![CDATA[
 @SuppressWarnings("serial")