fix | have distinct values in the id lookup table (#125)

* making the immutable table to have distinct value

Author: aman-bansal

hypertrace-core-graphql-attribute-store/src/main/java/org/hypertrace/core/graphql/attributes/CachingAttributeStore.java

@@ -18,7 +18,6 @@
 
 @Singleton
 class CachingAttributeStore implements AttributeStore {
-
   private final CachingAttributeClient cachingAttributeClient;
   private final IdLookup idLookup;
   private final GrpcContextBuilder grpcContextBuilder;

hypertrace-core-graphql-attribute-store/src/main/java/org/hypertrace/core/graphql/attributes/IdLookup.java

@@ -60,6 +60,9 @@ private Single<ImmutableTable<String, String, String>> loadMappingsForContext(
         .flatMap(
             idMappingLoader ->
                 idMappingLoader.loadMappings(key.getContext()).subscribeOn(this.boundedIoScheduler))
+        // This is added to have distinct values while building the
+        // immutable table in case of having duplicate id definitions
+        .distinct()
         .collect(
             ImmutableTable.toImmutableTable(
                 IdMapping::containingScope, IdMapping::foreignScope, IdMapping::idAttribute))