If you use the /status REST API you can find out precisely which TinkerPop version is currently supported. If you do something like
curl <my endpoint>:8182/status
You should see something like
{"status":"healthy","startTime":"Mon Dec 23 03:09:51 UTC 2019","dbEngineVersion":"1.0.2.1.R4","role":"writer","gremlin":{"version":"tinkerpop-3.4.1"},"sparql":{"version":"sparql-1.1"},"labMode":{"ObjectIndex":"disabled","Streams":"enabled","ReadWriteConflictDetection":"enabled"}}
UPDATED 2022-05-18
As an alternative to /status
if you are using the Neptune workbench (Jupyter notebooks) the %status
magic command will also produce the status information that includes the supported query language versions.