Fixed GetMessage Helper Method

[patilakshay227]

Issue

Consider following proto file content

message Bike {
  MetaInfo meta_info = 1;
  message MetaInfo {
    string manufacturer = 1;
  }
}

message Car {
    MetaInfo meta_info = 1;
    message MetaInfo {
      string manufacturer = 1;
      int32 seating_capactiy = 2;
    }
}

If GetMessage helper method is called with argument Car.MetaInfo.

In the existing version, it will iterate over the top-level message Bike first, remove the Bike. prefix, and try to find MetaInfo in Nested Messages of Bike which it would be able to find but it is incorrect as caller asked for Car.MetaInfo not Bike.MetaInfo.

Fix

Added a check to search for nested message only if prefix match with provided typeName.