@java.lang.Override
  protected Builder newBuilderForType(com.google.protobuf.GeneratedMessageV3.BuilderParent parent) {
    Builder builder = new Builder(parent);
    return builder;
  }
<pre>
A user-supplied resource id for this Product. If set, the server will
attempt to use this value as the resource id. If it is already in use, an
error is returned with code ALREADY_EXISTS. Must be at most 128 characters
long. It cannot contain the character `/`.
</pre>

<code>string product_id = 3;</code>

@return The bytes for productId.
java-vision/proto-google-cloud-vision-v1/src/main/java/com/google/cloud/vision/v1/CreateProductRequest.java