Some property editors do not support null values:
ByteEditor, ColorEditor, FloatEditor, FontEditor, LongEditor, ShortEditor
BooleanEditor.getJavaInitializationString() throws NPE.
ByteEditor.getJavaInitializationString() returns "((byte)null)".
ShortEditor.getJavaInitializationString() returns "((short)null)".
LongEditor.getJavaInitializationString() returns "nullL".
FloatEditor.getJavaInitializationString() returns "nullF".
ColorEditor.getJavaInitializationString() returns "new java.awt.Color()"
FontEditor.getJavaInitializationString() throws NPE.