public java.lang.String getRetailProductRecognitionIndex() {
        java.lang.Object ref = retailProductRecognitionIndex_;
        if (!(ref instanceof java.lang.String)) {
          com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
          java.lang.String s = bs.toStringUtf8();
          retailProductRecognitionIndex_ = s;
          return s;
        } else {
          return (java.lang.String) ref;
        }
      }
<pre>
Required. Resource name of RetailProductRecognitionIndex.
Format is
'projects/&#42;&#47;locations/&#42;&#47;retailCatalogs/&#42;&#47;retailProductRecognitionIndexes/&#42;'
</pre>

<code>
string retail_product_recognition_index = 1 [(.google.api.field_behavior) = REQUIRED];
</code>

@return The retailProductRecognitionIndex.
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/CustomProcessorSourceInfo.java