private com.google.protobuf.SingleFieldBuilderV3<
            com.google.protobuf.Duration,
            com.google.protobuf.Duration.Builder,
            com.google.protobuf.DurationOrBuilder>
        getTravelDurationFieldBuilder() {
      if (travelDurationBuilder_ == null) {
        travelDurationBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.protobuf.Duration,
                com.google.protobuf.Duration.Builder,
                com.google.protobuf.DurationOrBuilder>(
                getTravelDuration(), getParentForChildren(), isClean());
        travelDuration_ = null;
      }
      return travelDurationBuilder_;
    }
<pre>
Required. The maximum travel time in seconds. The maximum allowed value is
`3600s` (one hour). Format is `123s`.
</pre>

<code>
.google.protobuf.Duration travel_duration = 3 [(.google.api.field_behavior) = REQUIRED];
</code>
java-talent/proto-google-cloud-talent-v4beta1/src/main/java/com/google/cloud/talent/v4beta1/CommuteFilter.java