Update Caller.java

Author: egecansen

src/main/java/api_assured/Caller.java

@@ -187,7 +187,7 @@ private static <ErrorModel> ErrorModel getErrorObject(Response<?> response, Clas
              if (!StringUtilities.isBlank(bodyString)) {
                  if (errorModel.isAssignableFrom(String.class))
                      return (ErrorModel) bodyString;
-                 else return fromJsonString(bodyString, errorModel);
+                 else return MappingUtilities.Json.fromJsonString(bodyString, errorModel);
              }
             else
                 return null;