moved Filter into an IQueryable extension method

Author: shuebner-zeiss

src/JsonApiDotNetCore/Data/DefaultEntityRepository.cs

@@ -58,13 +58,7 @@ public virtual IQueryable<TEntity> Get()
 
         public virtual IQueryable<TEntity> Filter(IQueryable<TEntity> entities, FilterQuery filterQuery)
         {
-            if (filterQuery == null)
-                return entities;
-
-            if (filterQuery.IsAttributeOfRelationship)
-                return entities.Filter(new RelatedAttrFilterQuery(_jsonApiContext, filterQuery));
-
-            return entities.Filter(new AttrFilterQuery(_jsonApiContext, filterQuery));
+            return entities.Filter(_jsonApiContext, filterQuery);
         }
 
         public virtual IQueryable<TEntity> Sort(IQueryable<TEntity> entities, List<SortQuery> sortQueries)

src/JsonApiDotNetCore/Extensions/IQueryableExtensions.cs

@@ -77,6 +77,17 @@ private static IOrderedQueryable<TSource> CallGenericOrderMethod<TSource>(IQuery
             return (IOrderedQueryable<TSource>)result;
         }
 
+        public static IQueryable<TSource> Filter<TSource>(this IQueryable<TSource> source, IJsonApiContext jsonApiContext, FilterQuery filterQuery)
+        {
+            if (filterQuery == null)
+                return source;
+
+            if (filterQuery.IsAttributeOfRelationship)
+                return source.Filter(new RelatedAttrFilterQuery(jsonApiContext, filterQuery));
+
+            return source.Filter(new AttrFilterQuery(jsonApiContext, filterQuery));
+        }
+
         public static IQueryable<TSource> Filter<TSource>(this IQueryable<TSource> source, AttrFilterQuery filterQuery)
         {
             if (filterQuery == null)