public Builder setProductLabels(
        int index, com.google.cloud.vision.v1.Product.KeyValue.Builder builderForValue) {
      if (productLabelsBuilder_ == null) {
        ensureProductLabelsIsMutable();
        productLabels_.set(index, builderForValue.build());
        onChanged();
      } else {
        productLabelsBuilder_.setMessage(index, builderForValue.build());
      }
      return this;
    }
<pre>
Key-value pairs that can be attached to a product. At query time,
constraints can be specified based on the product_labels.

Note that integer values can be provided as strings, e.g. "1199". Only
strings with integer values can match a range-based restriction which is
to be supported soon.

Multiple values can be assigned to the same key. One product may have up to
500 product_labels.

Notice that the total number of distinct product_labels over all products
in one ProductSet cannot exceed 1M, otherwise the product search pipeline
will refuse to work for that ProductSet.
</pre>

<code>repeated .google.cloud.vision.v1.Product.KeyValue product_labels = 5;</code>
java-vision/proto-google-cloud-vision-v1/src/main/java/com/google/cloud/vision/v1/Product.java