Currently have started with docxj, but I have a lot problem with a simple example.
In my example I call 
	WordprocessingMLPackage wordMLPackage = WordprocessingMLPackage.createPackage();
	wordMLPackage.save(new java.io.File("hworld.docx") );
An the save throw the exception:
org.docx4j.openpackaging.exceptions.Docx4JException: Error marshalling Content_Types 
	at org.docx4j.openpackaging.io3.stores.ZipPartStore.saveContentTypes(ZipPartStore.java:217)
	at org.docx4j.openpackaging.io3.Save.save(Save.java:176)
	at org.docx4j.openpackaging.packages.OpcPackage.save(OpcPackage.java:604)
	at org.docx4j.openpackaging.packages.OpcPackage.save(OpcPackage.java:550)
	at org.docx4j.openpackaging.packages.OpcPackage.save(OpcPackage.java:523)
	at Main16.main(Main16.java:16)
Caused by: java.lang.NullPointerException
	at org.docx4j.openpackaging.contenttype.ContentTypeManager.marshal(ContentTypeManager.java:794)
	at org.docx4j.openpackaging.io3.stores.ZipPartStore.saveContentTypes(ZipPartStore.java:213)
	... 5 more
org.docx4j.openpackaging.exceptions.Docx4JException: Error marshalling Content_Types 
	at org.docx4j.openpackaging.io3.stores.ZipPartStore.saveContentTypes(ZipPartStore.java:217)
	at org.docx4j.openpackaging.io3.Save.save(Save.java:176)
	at org.docx4j.openpackaging.packages.OpcPackage.save(OpcPackage.java:604)
	at org.docx4j.openpackaging.packages.OpcPackage.save(OpcPackage.java:550)
	at org.docx4j.openpackaging.packages.OpcPackage.save(OpcPackage.java:523)
	at Main16.main(Main16.java:16)
Caused by: java.lang.NullPointerException
	at org.docx4j.openpackaging.contenttype.ContentTypeManager.marshal(ContentTypeManager.java:794)
	at org.docx4j.openpackaging.io3.stores.ZipPartStore.saveContentTypes(ZipPartStore.java:213)
	... 5 more
I don't why?
My Envrionment:
Eclipse Mars
JDK 1.8
docx4j-3.2.2.zip
			
		
