code: protected void onVisitFieldInsn(int opcode, String owner, String name, String descriptor) {
          super.visitFieldInsn(opcode, owner, name, descriptor);
      }
docs: Visits a field instruction.
  
  @param opcode     The visited opcode.
  @param owner      The field's owner.
  @param name       The field's name.
  @param descriptor The field's descriptor.