public Builder mergeTtl(com.google.protobuf.Duration value) {
      if (ttlBuilder_ == null) {
        if (expirationCase_ == 10
            && expiration_ != com.google.protobuf.Duration.getDefaultInstance()) {
          expiration_ =
              com.google.protobuf.Duration.newBuilder((com.google.protobuf.Duration) expiration_)
                  .mergeFrom(value)
                  .buildPartial();
        } else {
          expiration_ = value;
        }
        onChanged();
      } else {
        if (expirationCase_ == 10) {
          ttlBuilder_.mergeFrom(value);
        } else {
          ttlBuilder_.setMessage(value);
        }
      }
      expirationCase_ = 10;
      return this;
    }
<pre>
Input only. The TTL for this resource. The expiration time is computed:
now + TTL.
</pre>

<code>.google.protobuf.Duration ttl = 10 [(.google.api.field_behavior) = INPUT_ONLY];</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/CachedContent.java