private com.google.protobuf.SingleFieldBuilderV3<
            com.google.type.DateTime,
            com.google.type.DateTime.Builder,
            com.google.type.DateTimeOrBuilder>
        getDatetimeValueFieldBuilder() {
      if (datetimeValueBuilder_ == null) {
        if (!(valueCase_ == 3)) {
          value_ = com.google.type.DateTime.getDefaultInstance();
        }
        datetimeValueBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.type.DateTime,
                com.google.type.DateTime.Builder,
                com.google.type.DateTimeOrBuilder>(
                (com.google.type.DateTime) value_, getParentForChildren(), isClean());
        value_ = null;
      }
      valueCase_ = 3;
      onChanged();
      return datetimeValueBuilder_;
    }
<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