public Builder clearExpireTime() {
      if (expireTimeBuilder_ == null) {
        if (expirationCase_ == 9) {
          expirationCase_ = 0;
          expiration_ = null;
          onChanged();
        }
      } else {
        if (expirationCase_ == 9) {
          expirationCase_ = 0;
          expiration_ = null;
        }
        expireTimeBuilder_.clear();
      }
      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