public Builder mergeError(com.google.rpc.Status value) {
      if (errorBuilder_ == null) {
        if (((bitField0_ & 0x00001000) != 0)
            && error_ != null
            && error_ != com.google.rpc.Status.getDefaultInstance()) {
          getErrorBuilder().mergeFrom(value);
        } else {
          error_ = value;
        }
      } else {
        errorBuilder_.mergeFrom(value);
      }
      if (error_ != null) {
        bitField0_ |= 0x00001000;
        onChanged();
      }
      return this;
    }
<pre>
If set, represents the error message for the operation.
Note that filled-in image annotations are guaranteed to be
correct, even when `error` is set.
</pre>

<code>.google.rpc.Status error = 9;</code>
java-vision/proto-google-cloud-vision-v1/src/main/java/com/google/cloud/vision/v1/AnnotateImageResponse.java