Allow nulls for write elements in MXSerializer

https://issues.apache.org/jira/browse/MJAVADOC-793

Author: garydgregory

src/main/java/org/codehaus/plexus/util/xml/pull/MXSerializer.java

@@ -854,6 +854,9 @@ public void flush() throws IOException{
 // --- utility methods
 
 protectedvoidwriteAttributeValue(Stringvalue, Writerout) throwsIOException{
+if (value == null){
+return;
+ }
 // .[apostrophe and <, & escaped],
 finalcharquot = attributeUseApostrophe ? '\'' : '"';
 finalStringquotEntity = attributeUseApostrophe ? "&apos;" : "&quot;";
@@ -908,6 +911,9 @@ protected void writeAttributeValue(String value, Writer out) throws IOException
  }
 
 protectedvoidwriteElementContent(Stringtext, Writerout) throwsIOException{
+if (text == null){
+return;
+ }
 // escape '<', '&', ']]>', <32 if necessary
 intpos = 0;
 for (inti = 0; i < text.length(); i++){

src/test/java/org/codehaus/plexus/util/xml/pull/MXSerializerTest.java

@@ -1,5 +1,6 @@
 packageorg.codehaus.plexus.util.xml.pull;
 
+importjava.io.IOException;
 importjava.io.StringReader;
 importjava.io.StringWriter;
 importjava.util.Arrays;
@@ -55,4 +56,19 @@ private String expectedOutput(){
 out.append("</root>");
 returnout.toString();
  }
+
+/**
+ * Tests MJAVADOC-793.
+ */
+@Test
+publicvoidtestWriteNullValues() throwsIOException{
+// should be no-ops
+newMXSerializer().writeElementContent(null, null);
+newMXSerializer().writeAttributeValue(null, null);
+finalStringWriterstringWriter = newStringWriter();
+newMXSerializer().writeElementContent(null, stringWriter);
+assertEquals("", stringWriter.toString());
+newMXSerializer().writeAttributeValue(null, stringWriter);
+assertEquals("", stringWriter.toString());
+ }
 }