DATAMONGO-1491 - Polishing.

Remove variable before returning value. Add generics for list creation.

Original pull request: #412.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationExpressions.java

@@ -131,8 +131,7 @@ public interface AggregationExpressions {
 			}
 
 			NestedDelegatingExpressionAggregationOperationContext nea = new NestedDelegatingExpressionAggregationOperationContext(context);
-			Document mappedCondition = ((AggregationExpression) condition).toDocument(nea);
-			return mappedCondition;
+			return ((AggregationExpression) condition).toDocument(nea);
 		}
 
 		/**
@@ -224,7 +223,7 @@ public interface AggregationExpressions {
 			public AsBuilder filter(List<?> array) {
 
 				Assert.notNull(array, "Array must not be null!");
-				filter.input = new ArrayList(array);
+				filter.input = new ArrayList<Object>(array);
 				return this;
 			}
 
@@ -288,7 +287,5 @@ public interface AggregationExpressions {
 				return filter;
 			}
 		}
-
 	}
-
 }