private com.google.protobuf.SingleFieldBuilderV3<
              com.google.protobuf.Duration,
              com.google.protobuf.Duration.Builder,
              com.google.protobuf.DurationOrBuilder>
          getRepeatIntervalFieldBuilder() {
        if (repeatIntervalBuilder_ == null) {
          repeatIntervalBuilder_ =
              new com.google.protobuf.SingleFieldBuilderV3<
                  com.google.protobuf.Duration,
                  com.google.protobuf.Duration.Builder,
                  com.google.protobuf.DurationOrBuilder>(
                  getRepeatInterval(), getParentForChildren(), isClean());
          repeatInterval_ = null;
        }
        return repeatIntervalBuilder_;
      }
<pre>
Interval between the start of each scheduled TransferOperation. If
unspecified, the default value is 24 hours. This value may not be less than
1 hour.
</pre>

<code>.google.protobuf.Duration repeat_interval = 5;</code>
java-storage-transfer/proto-google-cloud-storage-transfer-v1/src/main/java/com/google/storagetransfer/v1/proto/TransferTypes.java