Thanks Eduard, now it is working in two different versions.

1.  Cache for Windows (x86-64) 2017.2.2 (Build 865U_SU) Mon Jul 9 2018 14:31:14 EDT
     USER>Write $system.Version.IsUnicode()
    1

2.  Cache for Windows (x86-64) 2018.1 (Build 179) Tue Sep 4 2018 00:04:51 EDT
      USER>Write $system.Version.IsUnicode()
      0

Yes, same version. Just downloaded from repo and imported GraphQL.xml.

Version: Cache for Windows (x86-64) 2017.2.2 (Build 865) Mon Jun 25 2018 10:45:31 EDT

Also  in Cache for Windows (x86-64) 2017.2 (Build 744) Fri Sep 29 2017 11:10:05 EDT

and getting the same error when import and compile GraphQL.xml.

After import an error occurred as below.

---------------------------
Studio
---------------------------
ERROR #6301: SAX XML Parser Error: invalid XML encoding declaration '' while processing Anonymous Stream at line 1 offset 32
  > ERROR #5490: Error running generator for method 'DispatchMap:GraphQL.REST.AbstractREST'
ERROR: %CSP.REST.cls(DispatchMap) of generated code compiling subclass 'GraphQL.REST.AbstractREST'
    > ERROR #5030: An error occurred while compiling class 'GraphQL.REST.AbstractREST'
---------------------------
OK   
---------------------------

I am using Cache 2017.2.2.

Any pointers will be a great help.

Thanks,