private com.google.protobuf.SingleFieldBuilderV3<
            com.google.type.DateTime,
            com.google.type.DateTime.Builder,
            com.google.type.DateTimeOrBuilder>
        getStartFieldBuilder() {
      if (startBuilder_ == null) {
        startBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.type.DateTime,
                com.google.type.DateTime.Builder,
                com.google.type.DateTimeOrBuilder>(getStart(), getParentForChildren(), isClean());
        start_ = null;
      }
      return startBuilder_;
    }
<pre>
Start date time.
</pre>

<code>.google.type.DateTime start = 1;</code>
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/DateTimeRange.java