title: Error: Not supported: indent-number when using jaxb2-maven-plugin with jdk8
body: <p>I have a project that was compiled with java6. It uses jaxb2-maven-plugin to generate XSD for web services.</p>
  
  <p>I am trying to port this project to compile/run with java8. In order to do that, I upgraded the jaxb2-maven-plugin version from 1.3.1 to 2.2</p>
  
  <p>however when I build my project using "mvn clean install" I get the following error:</p>
  
  <pre><code>--
  [INFO] XSD post-processing: Adding JavaDoc annotations in generated XSDs. 
  [INFO] Processing [4] java sources. 
  [ERROR] Execution failed. 
  [ERROR]  [Exception]: java.lang.IllegalArgumentException [Message]: Not supported: indent-number
               org.apache.xalan.processor.TransformerFactoryImpl.setAttribute(TransformerFactoryImpl.java:485)
               org.codehaus.mojo.jaxb2.schemageneration.XsdGeneratorHelper.getFactory(XsdGeneratorHelper.java:544)
               org.codehaus.mojo.jaxb2.schemageneration.XsdGeneratorHelper.getHumanReadableXml(XsdGeneratorHelper.java:440)
               org.codehaus.mojo.jaxb2.schemageneration.XsdGeneratorHelper.savePrettyPrintedDocument(XsdGeneratorHelper.java:508)
  --
  </code></pre>
  
  <p>I googled for this error and found that it was due to the old java6 having shipped with xalan transformer that supported this. But I am not sure how to fix this as I am using the plugin and not doing any transformation in my own code.</p>
  
  <p>any help appreciated.</p>