IdStory Identity Manager

version 9.7.10

How to reproduce:
Create a system configuration using standard database table connector
configure one attribute as timestamp with data type in schema java.sql.Timestamp
Configure a synchronization mapping and synchronization configuration (not recontiliation) for this system
Run the synchronization, stop it after a while
Go to sync. config and delete the value of the token.
Re-Run the sync.
It will crash with fallowing message:

Synchronization was started in 2019-10-30T14:33:19.935.
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Synchronization will use inner connector synchronization implementation.
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Error during synchronization
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org.identityconnectors.framework.common.exceptions.ConnectorException: Can not read from the table or view 'name_of_the_table'.
    at net.tirasa.connid.bundles.db.table.DatabaseTableConnector.sync(DatabaseTableConnector.java:766)
    at org.identityconnectors.framework.impl.api.local.operations.SyncImpl.sync(SyncImpl.java:137)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.identityconnectors.framework.impl.api.local.operations.ConnectorAPIOperationRunnerProxy.invoke(ConnectorAPIOperationRunnerProxy.java:98)
    at com.sun.proxy.$Proxy386.sync(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.identityconnectors.framework.impl.api.local.operations.ThreadClassLoaderManagerProxy.invoke(ThreadClassLoaderManagerProxy.java:96)
    at com.sun.proxy.$Proxy386.sync(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.identityconnectors.framework.impl.api.BufferedResultsProxy$BufferedResultsHandler.run(BufferedResultsProxy.java:165)
Caused by: org.postgresql.util.PSQLException: ERROR: operator does not exist: timestamp without time zone > character varying
  Hint: No operator matches the given name and argument type(s). You might need to add explicit type casts.
  Position: 158

The problem seems to be that the empty form field from GUI is saved as some white character or an empty string. But this is just a theory, not confirmed.