// at runtime, a runtime error should be raised when the unsupported
// element is instantiated. Otherwise, no error is thrown.
ConstantPoolGen cpg = classGen.getConstantPool();
InstructionList il = methodGen.getInstructionList();
final int unsupportedElem = cpg.addMethodref(BASIS_LIBRARY_CLASS, "unsupported_ElementF",
"(" + STRING_SIG + "Z)V");
il.append(new PUSH(cpg, getQName().toString()));
il.append(new PUSH(cpg, _isExtension));
il.append(new INVOKESTATIC(unsupportedElem));
}