fix addEmptyString in performance.xml

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

@@ -26,6 +26,8 @@ It is much better to use one of the type-specific toString() methods instead.
                 <value>
 <![CDATA[
 //AdditiveExpression/PrimaryExpression/PrimaryPrefix/Literal[@Image='""' and not(ancestor::Annotation)]
+|
+//AdditiveExpression/PrimaryExpression/PrimaryPrefix/Name[contains(string-join(//VariableInitializer/Expression/PrimaryExpression/PrimaryPrefix/Literal[@Image='""']/../../../../../VariableDeclaratorId/@Name,','),@Image)]
 ]]>
                 </value>
             </property>