Reported by Martin Buchholz
Here is the pertinent line:

Caused by: java.lang.NullPointerException
	at com.sun.tools.javac.util.CloseableURLClassLoader.close(CloseableURLClassLoader.java:73)


Here is the full strack trace.


ava.io.IOException: cannot close class loader
	at com.sun.tools.javac.util.CloseableURLClassLoader.close(CloseableURLClassLoader.java:77)
	at com.sun.tools.javac.processing.JavacProcessingEnvironment.close(JavacProcessingEnvironment.java:1008)
	at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:752)
	at com.sun.tools.javac.main.Main.compile(Main.java:385)
	at com.sun.tools.javac.main.Main.compile(Main.java:309)
	at com.sun.tools.javac.main.Main.compile(Main.java:297)
	at com.sun.tools.javac.Main.compile(Main.java:82)
	at com.sun.tools.apt.main.Main.compile(Main.java:1089)
	at com.sun.tools.apt.Main.processing(Main.java:113)
	at com.sun.tools.apt.Main.process(Main.java:103)
	at com.sun.tools.apt.Main.process(Main.java:85)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:616)
	at com.sun.tools.internal.jxc.SchemaGenerator$Runner.main(SchemaGenerator.java:215)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:616)
	at com.sun.tools.internal.jxc.SchemaGenerator.run(SchemaGenerator.java:153)
	at com.sun.tools.internal.jxc.SchemaGenerator.run(SchemaGenerator.java:63)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:616)
	at com.sun.jck.lib.SchemaGen.generate(SchemaGen.java:84)
	at com.sun.jck.lib.SchemaGenInvoker.invoke(SchemaGenInvoker.java:114)
	at com.sun.jck.lib.Invoker.execute(Invoker.java:66)
	at com.sun.jck.lib.CompositeInvoker.invoke(CompositeInvoker.java:46)
	at com.sun.jck.lib.Invoker.execute(Invoker.java:66)
	at com.sun.jck.lib.Jxc.execute(Jxc.java:83)
	at com.sun.jck.lib.JaxbCommand.run(JaxbCommand.java:74)
	at com.sun.jck.lib.JaxbCommand.main(JaxbCommand.java:96)
Caused by: java.lang.NullPointerException
	at com.sun.tools.javac.util.CloseableURLClassLoader.close(CloseableURLClassLoader.java:73)
	... 33 more