public Builder clearDatetimeValue() {
      if (datetimeValueBuilder_ == null) {
        if (valueCase_ == 3) {
          valueCase_ = 0;
          value_ = null;
          onChanged();
        }
      } else {
        if (valueCase_ == 3) {
          valueCase_ = 0;
          value_ = null;
        }
        datetimeValueBuilder_.clear();
      }
      return this;
    }
<pre>
Datetime type value.
</pre>

<code>.google.type.DateTime datetime_value = 3;</code>
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/FacetValue.java