docs: public FieldDescriptor getFieldDescriptor(@SlashedClassName String className, String name, String signature, boolean isStatic) {
          FieldDescriptor fieldDescriptor = new FieldDescriptor(className, name, signature, isStatic);
          FieldDescriptor existing = fieldDescriptorMap.get(fieldDescriptor);
          if (existing == null) {
              fieldDescriptorMap.put(fieldDescriptor, fieldDescriptor);
              existing = fieldDescriptor;
          }
          return existing;
      }