To add, there are some settings to help you but these are global settings. I would recommend go with the above options and see what best suits you.
watt.server.json.decodeIntegerAsLong
Converts an integer that Integration Server retrieves from JSON content to either a
Long or Integer Java wrapper type. If this parameter is set to true, Integration Server
converts the JSON integer to a Long Java wrapper type. If this parameter is set to false,
Integration Server converts the JSON integer to a Integer Java wrapper type. The default
is true (Long).
watt.server.json.decodeRealAsDouble
Converts a real number that Integration Server retrieves from JSON content to either
a Float or Double Java wrapper type. If this parameter is set to true, Integration Server
converts the real number to a Double Java wrapper type. If this parameter is set to
false, Integration Server converts the real number to a Float Java wrapper type. The
default is true (Double).
watt.server.json.decodeRealAsString
Converts a real number that Integration Server retrieves from JSON content to String. If
this parameter is set to true, Integration Server converts the real number to a String. If
this parameter is set to false, Integration Server does not convert the real numbers to
String instead, real numbers are converted to either Float or Double Java wrapper type
depending on the values specified in decodeRealAsDouble . The default is false.