public Builder setExpireTime(com.google.protobuf.Timestamp.Builder builderForValue) {
      if (expireTimeBuilder_ == null) {
        expiration_ = builderForValue.build();
        onChanged();
      } else {
        expireTimeBuilder_.setMessage(builderForValue.build());
      }
      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