refactor: simplify the deep name logic (#165)

Author: smyrick

src/main/kotlin/com/expedia/graphql/extensions/deepName.kt

@@ -1,8 +1,7 @@
 package com.expedia.graphql.extensions
 
-import graphql.schema.GraphQLList
-import graphql.schema.GraphQLNonNull
 import graphql.schema.GraphQLType
+import graphql.schema.GraphQLTypeUtil
 
 /**
  * Useful public extension that renders a readable string from the given
@@ -12,8 +11,4 @@ import graphql.schema.GraphQLType
  * @return a string representation of the type taking list and non-null into account
  */
 val GraphQLType.deepName: String
-    get() = when {
-        this is GraphQLNonNull -> "${wrappedType.deepName}!"
-        this is GraphQLList -> "[${wrappedType.deepName}]"
-        else -> name
-    }
+    get() = GraphQLTypeUtil.simplePrint(this)