[java] EmptyCatchBlock may ignore blocks based on exception name

- Allow the developer to setup a regular expression for exception names
to be ignored by the rule.
 - Fixes #413

pmd-java/src/main/resources/rulesets/java/empty.xml

@@ -30,10 +30,12 @@ or reported.
  [FormalParameter/Type/ReferenceType
    /ClassOrInterfaceType[@Image != 'InterruptedException' and @Image != 'CloneNotSupportedException']
  ]
+ [FormalParameter/VariableDeclaratorId[not(matches(@Image, $allowExceptionNameRegex))]]
  ]]>
              </value>
           </property>
           <property name="allowCommentedBlocks" type="Boolean" description="Empty blocks containing comments will be skipped" value="false"/>
+          <property name="allowExceptionNameRegex" type="String" description="Empty blocks catching exceptions with names matching this regular expression will be skipped" value="^$"/>
       </properties>
       <example>
   <![CDATA[

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/empty/xml/EmptyCatchBlock.xml

@@ -167,4 +167,21 @@ Javadoc comment is not OK
     </test-code>
  
     <!-- END Commented blocks -->
+    <test-code>
+        <description><![CDATA[
+Allow to ignore exceptions by name
+     ]]></description>
+        <rule-property name="allowExceptionNameRegex">^(ignored|expected)$</rule-property>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public class Foo {
+ void foo() {
+  try {
+  } catch (NullPointerException expected) {
+  } catch (IllegalArgumentException ignored) {
+  }
+ }
+}
+     ]]></code>
+    </test-code>
 </test-data>