// push the pk field
mv.visitVarInsn(ALOAD, 0);
mv.visitFieldInsn(GETFIELD, implClassName, UNKNOWN_PK_NAME, UNKNOWN_PK_TYPE.getDescriptor());
// return the pk field (from the stack)
mv.visitInsn(UNKNOWN_PK_TYPE.getOpcode(IRETURN));
} else {
// We have a primary key class defined. For every field that matches one of the
// defined CMP fields, we generate code to copy that value into the corresponding
// field of the primary key class.
String pkImplName = primKeyClass.getName().replace('.', '/');