7 classes are annotated with JsonRpcMethod in JSON-RPC 2.x

AddPermissionToRole in modules/jsonrpc_core/src/Plugin/jsonrpc/Method/AddPermissionToRole.php

A method to add permissions to a role.

FirstMethod in tests/modules/jsonrpc_test/src/Plugin/jsonrpc/Method/FirstMethod.php

First test method.

ListPermissions in modules/jsonrpc_core/src/Plugin/jsonrpc/Method/ListPermissions.php

RPC method to list all the permissions.

Plugins in modules/jsonrpc_core/src/Plugin/jsonrpc/Method/Plugins.php

Lists the plugin definitions of a given type.

RouteBuilder in modules/jsonrpc_core/src/Plugin/jsonrpc/Method/RouteBuilder.php

RPC method to rebuild the routes.

SecondMethod in tests/modules/jsonrpc_test/src/Plugin/jsonrpc/Method/SecondMethod.php

Second test method.

ThirdMethod in tests/modules/jsonrpc_test/src/Plugin/jsonrpc/Method/ThirdMethod.php

Third test method.