B2B-2658: Implement GraphQL Resolver Cache for Customer query

- updated interface doc

Author: rganin

app/code/Magento/GraphQlResolverCache/Model/Resolver/Result/CacheKey/GenericFactorProviderInterface.php

@@ -24,7 +24,12 @@ public function getFactorName(): string;
     /**
      * Returns the runtime value that should be used as factor.
      *
+     * Throws an Exception if factor value cannot be resolved.
+     *
      * @param ContextInterface $context
+     *
+     * @throws \Exception
+     *
      * @return string
      */
     public function getFactorValue(ContextInterface $context): string;

app/code/Magento/GraphQlResolverCache/Model/Resolver/Result/CacheKey/ParentValueFactorProviderInterface.php

@@ -37,8 +37,13 @@ public function isRequiredOrigData(): bool;
     /**
      * Returns the runtime value that should be used as factor.
      *
+     * Throws an Exception if factor value cannot be resolved.
+     *
      * @param ContextInterface $context
      * @param array $parentValue
+     *
+     * @throws \Exception
+     *
      * @return string
      */
     public function getFactorValue(ContextInterface $context, array $parentValue): string;