public Builder mergeValidAfterDuration(com.google.protobuf.Duration value) {
        if (validAfterDurationBuilder_ == null) {
          if (startTimingConstraintsCase_ == 3
              && startTimingConstraints_ != com.google.protobuf.Duration.getDefaultInstance()) {
            startTimingConstraints_ =
                com.google.protobuf.Duration.newBuilder(
                        (com.google.protobuf.Duration) startTimingConstraints_)
                    .mergeFrom(value)
                    .buildPartial();
          } else {
            startTimingConstraints_ = value;
          }
          onChanged();
        } else {
          if (startTimingConstraintsCase_ == 3) {
            validAfterDurationBuilder_.mergeFrom(value);
          } else {
            validAfterDurationBuilder_.setMessage(value);
          }
        }
        startTimingConstraintsCase_ = 3;
        return this;
      }
<pre>
Optional. A relative time after which resources may be created.
</pre>

<code>
.google.protobuf.Duration valid_after_duration = 3 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-tpu/proto-google-cloud-tpu-v2/src/main/java/com/google/cloud/tpu/v2/QueuedResource.java