[MSHARED-610] PrettyPrintXMLWriter internally uses java.io.PrintWrite…

…r without checking for any errors.

o Updated to restore JDK compatibility by removing calls to constructors
  only available since Java 7.



git-svn-id: https://svn.apache.org/repos/asf/maven/shared/trunk@1777864 13f79535-47bb-0310-9956-ffa450edef68

maven-shared-utils/src/main/java/org/apache/maven/shared/utils/xml/Xpp3Dom.java

@@ -385,7 +385,7 @@ public String toString()
         catch ( final IOException e )
         {
             // JDK error in StringWriter.
-            throw new AssertionError( "Unexpected IOException from StringWriter.", e );
+            throw (AssertionError) new AssertionError( "Unexpected IOException from StringWriter." ).initCause( e );
         }
     }
 
@@ -403,7 +403,7 @@ public String toUnescapedString()
         catch ( final IOException e )
         {
             // JDK error in StringWriter.
-            throw new AssertionError( "Unexpected IOException from StringWriter.", e );
+            throw (AssertionError) new AssertionError( "Unexpected IOException from StringWriter." ).initCause( e );
         }
     }