public Builder mergeExpireTime(com.google.protobuf.Timestamp value) {
      if (expireTimeBuilder_ == null) {
        if (expirationCase_ == 9
            && expiration_ != com.google.protobuf.Timestamp.getDefaultInstance()) {
          expiration_ =
              com.google.protobuf.Timestamp.newBuilder((com.google.protobuf.Timestamp) expiration_)
                  .mergeFrom(value)
                  .buildPartial();
        } else {
          expiration_ = value;
        }
        onChanged();
      } else {
        if (expirationCase_ == 9) {
          expireTimeBuilder_.mergeFrom(value);
        } else {
          expireTimeBuilder_.setMessage(value);
        }
      }
      expirationCase_ = 9;
      return this;
    }
<pre>
Timestamp of when this resource is considered expired.
This is *always* provided on output, regardless of what was sent
on input.
</pre>

<code>.google.protobuf.Timestamp expire_time = 9;</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/CachedContent.java