Using new xmlns.jcp.org namespace on composites causes java.lang.NullPointerException at java.util.concurrent.ConcurrentHashMap.putIfAbsent
问题 I am reading The Java EE 7 Tutorial from http://docs.oracle.com/javaee/7/tutorial/doc/jsf-facelets005.htm#GIQZR After I typed the example code in the chapter 8.5 Composite Components in my IDE and run the example on GlassFish4.0, I got an error java.lang.NullPointerException at java.util.concurrent.ConcurrentHashMap.putIfAbsent(ConcurrentHashMap.java:1078) at com.sun.faces.util.Cache.get(Cache.java:116) at com.sun.faces.application.view.FaceletViewHandlingStrategy.getComponentMetadata