public Builder clearUpdateMask() {
      bitField0_ = (bitField0_ & ~0x00000001);
      updateMask_ = null;
      if (updateMaskBuilder_ != null) {
        updateMaskBuilder_.dispose();
        updateMaskBuilder_ = null;
      }
      onChanged();
      return this;
    }
<pre>
Required. Field mask is used to specify the fields to be overwritten in the
Event resource by the update.
The fields specified in the update_mask are relative to the resource, not
the full request. A field will be overwritten if it is in the mask. If the
user does not provide a mask then all fields will be overwritten.
</pre>

<code>.google.protobuf.FieldMask update_mask = 1 [(.google.api.field_behavior) = REQUIRED];
</code>
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/UpdateEventRequest.java