Deadlock with concurrent requests to Microsoft SQL Server

Issue

When concurrent request queries are issued to Microsoft SQL Server, one request query succeeds, whereas the other fails with error message:

2020-11-24T14:55:09.095Z keycloak INFO  [com.XYZcompany.keycloak.register.UsersManagementResourceProvider] (default task-2) Creating user with XXX:RegisterUserRequest(username=rh1-1-0000, roles=null)
2020-11-24T14:55:13.363Z keycloak WARN  [org.hibernate.engine.jdbc.spi.SqlExceptionHelper] (default task-1) SQL Error: 1205, SQLState: 40001
2020-11-24T14:55:13.364Z keycloak ERROR [org.hibernate.engine.jdbc.spi.SqlExceptionHelper] (default task-1) Transaction (Process ID 54) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction.
2020-11-24T14:55:13.373Z keycloak ERROR [org.keycloak.services.error.KeycloakErrorHandler] (default task-1) Uncaught server error: javax.persistence.OptimisticLockException: org.hibernate.exception.LockAcquisitionException: could not execute query
    at org.hibernate.internal.ExceptionConverterImpl.wrapLockException(ExceptionConverterImpl.java:277)
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:98)
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181)
    at org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1514)
    at org.hibernate.query.Query.getResultList(Query.java:132)
    at org.keycloak.models.jpa.UserAdapter.getRoleMappings(UserAdapter.java:468)
    at org.keycloak.models.jpa.UserAdapter.hasRole(UserAdapter.java:420)
    at org.keycloak.models.jpa.UserAdapter.grantRole(UserAdapter.java:434)
    at org.keycloak.models.utils.DefaultRoles.addDefaultRoles(DefaultRoles.java:48)
    at org.keycloak.models.jpa.JpaUserProvider.addUser(JpaUserProvider.java:107)
    at org.keycloak.models.jpa.JpaUserProvider.addUser(JpaUserProvider.java:127)
    at org.keycloak.storage.UserStorageManager.addUser(UserStorageManager.java:151)
    at org.keycloak.models.cache.infinispan.UserCacheSession.addUser(UserCacheSession.java:768)
    at com.XYZcompany.keycloak.register.UsersManagementResourceProvider.createUser(UsersManagementResourceProvider.java:221)
    at com.XYZcompany.keycloak.register.UsersManagementResourceProvider.registerUser(UsersManagementResourceProvider.java:138)
    ...
    ...
Caused by: org.hibernate.exception.LockAcquisitionException: could not execute query
    at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:123)
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:113)
    at org.hibernate.loader.Loader.doList(Loader.java:2692)
    ...
Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: Transaction (Process ID 54) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction.
    at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:259)
    at com.microsoft.sqlserver.jdbc.SQLServerResultSet$FetchBuffer.nextRow(SQLServerResultSet.java:6388)
    at com.microsoft.sqlserver.jdbc.SQLServerResultSet.fetchBufferNext(SQLServerResultSet.java:1647)
    at com.microsoft.sqlserver.jdbc.SQLServerResultSet.next(SQLServerResultSet.java:988)
    at org.jboss.jca.adapters.jdbc.WrappedResultSet.next(WrappedResultSet.java:2689)
    at org.hibernate.loader.Loader.processResultSet(Loader.java:986)
    at org.hibernate.loader.Loader.doQuery(Loader.java:948)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:340)
    at org.hibernate.loader.Loader.doList(Loader.java:2689)
    ...