private com.google.protobuf.SingleFieldBuilderV3<
              com.google.protobuf.Timestamp,
              com.google.protobuf.Timestamp.Builder,
              com.google.protobuf.TimestampOrBuilder>
          getValidAfterTimeFieldBuilder() {
        if (validAfterTimeBuilder_ == null) {
          if (!(startTimingConstraintsCase_ == 4)) {
            startTimingConstraints_ = com.google.protobuf.Timestamp.getDefaultInstance();
          }
          validAfterTimeBuilder_ =
              new com.google.protobuf.SingleFieldBuilderV3<
                  com.google.protobuf.Timestamp,
                  com.google.protobuf.Timestamp.Builder,
                  com.google.protobuf.TimestampOrBuilder>(
                  (com.google.protobuf.Timestamp) startTimingConstraints_,
                  getParentForChildren(),
                  isClean());
          startTimingConstraints_ = null;
        }
        startTimingConstraintsCase_ = 4;
        onChanged();
        return validAfterTimeBuilder_;
      }
<pre>
Optional. An absolute time after which resources may be created.
</pre>

<code>
.google.protobuf.Timestamp valid_after_time = 4 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-tpu/proto-google-cloud-tpu-v2/src/main/java/com/google/cloud/tpu/v2/QueuedResource.java