register assumeState and fix README

Author: konnov

json-rpc/README.md

@@ -724,13 +724,13 @@ Execute the following command:
 $ curl -X POST http://localhost:8822/rpc \
   -H "Content-Type: application/json" \
   -d '{"jsonrpc":"2.0","method":"assumeState",
-       "params":{"sessionId":"1","checkEnabled":true,"equalities": {"x":{"#bigint":"1"}}},"id":4}'
+       "params":{"sessionId":"1","checkEnabled":true,"equalities": {"x":{"#bigint":"0"}}},"id":4}'
 ```
 
 It produces the following output:
 
 ```json  
-{"jsonrpc":"2.0","id":2,"result":{"sessionId":"1","snapshotId":3,"status":"ENABLED"}}
+{"jsonrpc":"2.0","id":4,"result":{"sessionId":"1","snapshotId":5,"status":"ENABLED"}}
 ```
 
 

json-rpc/src/main/scala/com/github/apalachemc/apalache/jsonrpc/JsonRpcServer.scala

@@ -830,6 +830,12 @@ class JsonRpcServlet(service: ExplorationService) extends HttpServlet with LazyL
               .fold(errorMessage => Left(ServiceError(JsonRpcCodes.INVALID_PARAMS, errorMessage)),
                   serviceParams => service.assumeTransition(serviceParams))
 
+          case "assumeState" =>
+            new JsonParameterParser(mapper)
+              .parseAssumeState(paramsNode)
+              .fold(errorMessage => Left(ServiceError(JsonRpcCodes.INVALID_PARAMS, errorMessage)),
+                  serviceParams => service.assumeState(serviceParams))
+
           case "nextStep" =>
             new JsonParameterParser(mapper)
               .parseNextStep(paramsNode)