Added fetch attribute by id in Attribute Store (#171)

Author: anujgoyal1

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

@@ -13,6 +13,8 @@ public interface AttributeStore {
 
   Single<AttributeModel> getIdAttribute(GraphQlRequestContext context, String scope);
 
+  Single<AttributeModel> getAttributeById(GraphQlRequestContext context, String attributeId);
+
   Single<AttributeModel> getForeignIdAttribute(
       GraphQlRequestContext context, String scope, String foreignScope);
 

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

@@ -86,6 +86,16 @@ public Single<AttributeModel> getForeignIdAttribute(
         .flatMap(key -> this.get(context, scope, key));
   }
 
+  @Override
+  public Single<AttributeModel> getAttributeById(
+      GraphQlRequestContext context, String attributeId) {
+    return grpcContextBuilder
+        .build(context)
+        .call(() -> cachingAttributeClient.get(attributeId))
+        .mapOptional(this.translator::translate)
+        .switchIfEmpty(Single.error(this.buildErrorForMissingAttributeId(attributeId)));
+  }
+
   @Override
   public Completable create(
       final GraphQlRequestContext context, final List<AttributeMetadata> attributes) {
@@ -139,6 +149,11 @@ private NoSuchElementException buildErrorForMissingAttribute(String scope, Strin
         String.format("No attribute available for scope '%s' and key '%s'", scope, key));
   }
 
+  private NoSuchElementException buildErrorForMissingAttributeId(String attributeId) {
+    return new NoSuchElementException(
+        String.format("No attribute available for attribute id '%s'", attributeId));
+  }
+
   private NoSuchElementException buildErrorForMissingForeignScopeMapping(
       String scope, String foreignScope) {
     return new NoSuchElementException(