1. create a source model by importing from testing Salesforce account; preview data of one table (Modeling -> Preview data) - this works (select * from "sf"."salesforce"."Account")
2. create a VDB with the source model; deploy, execute (use the same sql query) - this results in a error:

org.teiid.resource.adapter.file.FileConnectionImpl cannot be cast to org.teiid.translator.salesforce.SalesforceConnection

Console output:
13:46:09,114 ERROR [org.teiid.CONNECTOR] (Worker5_QueryProcessorQueue18) Connector worker process failed for atomic-request=oZbg6bQY7MUO.0.0.5: java.lang.ClassCastException: org.teiid.resource.adapter.file.FileConnectionImpl cannot be cast to org.teiid.translator.salesforce.SalesforceConnection
at org.teiid.translator.salesforce.SalesForceExecutionFactory.createResultSetExecution(SalesForceExecutionFactory.java:60)
at org.teiid.translator.ExecutionFactory.createExecution(ExecutionFactory.java:304) [teiid-api-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.datamgr.ConnectorWorkItem.execute(ConnectorWorkItem.java:245) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.process.DataTierTupleSource.getResults(DataTierTupleSource.java:444) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.process.DataTierTupleSource$1.call(DataTierTupleSource.java:157) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.process.DataTierTupleSource$1.call(DataTierTupleSource.java:154) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) [rt.jar:1.7.0_25]
at java.util.concurrent.FutureTask.run(FutureTask.java:166) [rt.jar:1.7.0_25]
at org.teiid.dqp.internal.process.FutureWork.run(FutureWork.java:58) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.process.DQPWorkContext.runInContext(DQPWorkContext.java:269) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.process.ThreadReuseExecutor$RunnableWrapper.run(ThreadReuseExecutor.java:119) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.process.ThreadReuseExecutor$3.run(ThreadReuseExecutor.java:214) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_25]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_25]
at java.lang.Thread.run(Thread.java:724) [rt.jar:1.7.0_25]

13:46:09,116 ERROR [org.teiid.PROCESSOR] (Worker4_QueryProcessorQueue19) TEIID30019 Unexpected exception for request oZbg6bQY7MUO.0: java.lang.ClassCastException: org.teiid.resource.adapter.file.FileConnectionImpl cannot be cast to org.teiid.translator.salesforce.SalesforceConnection
at org.teiid.translator.salesforce.SalesForceExecutionFactory.createResultSetExecution(SalesForceExecutionFactory.java:60)
at org.teiid.translator.ExecutionFactory.createExecution(ExecutionFactory.java:304) [teiid-api-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.datamgr.ConnectorWorkItem.execute(ConnectorWorkItem.java:245) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.process.DataTierTupleSource.getResults(DataTierTupleSource.java:444) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.process.DataTierTupleSource$1.call(DataTierTupleSource.java:157) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.process.DataTierTupleSource$1.call(DataTierTupleSource.java:154) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) [rt.jar:1.7.0_25]
at java.util.concurrent.FutureTask.run(FutureTask.java:166) [rt.jar:1.7.0_25]
at org.teiid.dqp.internal.process.FutureWork.run(FutureWork.java:58) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.process.DQPWorkContext.runInContext(DQPWorkContext.java:269) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.process.ThreadReuseExecutor$RunnableWrapper.run(ThreadReuseExecutor.java:119) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at org.teiid.dqp.internal.process.ThreadReuseExecutor$3.run(ThreadReuseExecutor.java:214) [teiid-engine-8.4.1-redhat-2.jar:8.4.1-redhat-2]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_25]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_25]
at java.lang.Thread.run(Thread.java:724) [rt.jar:1.7.0_25]