Fix intermittent ArrayIndexOutOfBoundsException during stderr processing (#303)

* Fix intermittent ArrayIndexOutOfBoundsException during stderr processing

The same StreamConsumer instance was shared between the stdout and stderr
StreamPumper threads in CommandLineUtils.executeCommandLine(). Since
StreamConsumer has non-thread-safe mutable state (StringBuilder, File,
int fields), concurrent access from both threads caused
ArrayIndexOutOfBoundsException inside StringBuilder's System.arraycopy.

Use separate StreamConsumer instances for stdout and stderr to eliminate
the race condition.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Use synchronized on shared StreamConsumer instead of separate instances

Address review feedback: use a single shared StreamConsumer with
synchronized consumeLine() to protect both the consumer's internal
state and the buildContext writes from concurrent access by the
stdout and stderr StreamPumper threads.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: gnodet

cxf-xjc-plugin/src/main/java/org/apache/cxf/maven_plugin/AbstractXSDToJavaMojo.java

@@ -553,8 +553,8 @@ private int runForked(XsdOption option, String outputDir) throws Exception {
             int linenum;
             int column;
             StringBuilder message = new StringBuilder();
-            
-            public void consumeLine(String line) {
+
+            public synchronized void consumeLine(String line) {
                 if (getLog().isDebugEnabled()) {
                     getLog().debug(line);
                 }
@@ -593,7 +593,7 @@ public void consumeLine(String line) {
             getLog().debug(e);
             throw new MojoExecutionException(e.getMessage(), e);
         }
-        
+
 
         String cmdLine = CommandLineUtils.toString(cmd.getCommandline());
 
@@ -609,5 +609,5 @@ public void consumeLine(String line) {
         file.delete();
         return 0;
     }
-    
+
 }