Oh Dear!

but Memory was expensive.
But my first DSM-like OS on VAX was only ~ 80KB code at run time. (40+ years back)
All the rest for Partitions and Buffers,  . 

Fully with you.
But in migration, you have no choice.
With several thousands of Globals, there is no chance to find out
if some crazy chap had used it decades ago.
When I saw it the first time I must have looked like Kong Kong.

Does it work if you call your class with full reference? I mean not for Login?
NOT found is suspicious somehow

Another idea:
Just to see that the port is open and you are on IRIS  you may try to access
over ODBC/JDBC gateway any table in %SYS

if you insist on that line you need

Set Jsonobj="{""Doctype"":""ADT^A01"",""PatientId"":""123"",""PatientName"":""Alex""}"