Handle raw Map type

Author: jhaber

src/main/kotlin/com/coxautodev/graphql/tools/PropertyMapResolver.kt

@@ -14,10 +14,17 @@ internal class PropertyMapResolver(field: FieldDefinition, search: FieldResolver
 
     var mapGenericValue : JavaType = getMapGenericType(relativeTo)
 
+    /**
+     * Takes a type which implements Map and tries to find the
+     * value type of that map. For some reason, mapClass is losing
+     * its generics somewhere along the way and is always a raw
+     * type
+     */
     fun getMapGenericType(mapClass : JavaType) : JavaType {
         val resolvedType = TypeResolver().resolve(mapClass)
 
-        return resolvedType.typeParametersFor(Map::class.java)[1]
+        val typeParameters = resolvedType.typeParametersFor(Map::class.java)
+        return typeParameters.elementAtOrElse(1) { Object::class.java }
     }
 
     override fun createDataFetcher(): DataFetcher<*> {