DynamicMessage.java 文件源码

public Builder clearField(FieldDescriptor field) {
  verifyContainingType(field);
  ensureIsMutable();
  OneofDescriptor oneofDescriptor = field.getContainingOneof();
  if (oneofDescriptor != null) {
    int index = oneofDescriptor.getIndex();
    if (oneofCases[index] == field) {
      oneofCases[index] = null;
    }
  }
  fields.clearField(field);
  return this;
}