docs: public static FieldAnnotation isWrite(Instruction ins, ConstantPoolGen cpg) {
          if (ins instanceof PUTFIELD || ins instanceof PUTSTATIC) {
              FieldInstruction fins = (FieldInstruction) ins;
              String className = fins.getClassName(cpg);
              return new FieldAnnotation(className, fins.getName(cpg), fins.getSignature(cpg), fins instanceof PUTSTATIC);
          } else {
              return null;
          }
      }