Factory actually produces something

git-svn-id: https://develop.sub.uni-goettingen.de/repos/textgrid/trunk/services/aggregator@14091 7c539038-3410-0410-b1ec-0f2a7bf1c452

src/main/java/info/textgrid/services/aggregator/tree/AggregationTreeFactory.java

@@ -37,4 +37,12 @@ protected void walkAggregation(final ObjectType aggregation,
 		stack.pop();
 	}
 
+	protected Aggregation getRoot() {
+		return root;
+	}
+
+	public static Aggregation create(final ObjectType root) {
+		return new AggregationTreeFactory(root).getRoot();
+	}
+
 }