Index: src/main/java/common/javax/swing/JEditorPane.java =================================================================== --- src/main/java/common/javax/swing/JEditorPane.java (revision 490282) +++ src/main/java/common/javax/swing/JEditorPane.java (working copy) @@ -259,6 +259,11 @@ public static void registerEditorKitForContentType(final String type, final String editorKitName, final ClassLoader loader) { + + if (type == null || editorKitName == null) { + throw new NullPointerException(); + } + int index = contentTypes.indexOf(type); if (index >= 0) { contentTypes.remove(index);