Merge pull request debezium#25 in N4FRA/debezium from DSCON-117_DBCon…

…nector_exception to master

Squashed commit of the following:

commit 2cb8126b258cae75547dd2fc9b45177533169fa9
Author: AndreyIg <gnyiny@gmail.com>
Date:   Mon Feb 3 13:45:38 2020 -0800

    fix smallest scn calculation

commit 4bf0b69
Merge: 8023485 605d22f
Author: AndreyIg <gnyiny@gmail.com>
Date:   Fri Jan 24 07:37:32 2020 -0800

    Merge branch 'master' into DBZ-137_candidate_merge_branch

commit 605d22f
Merge: 276c19b e68ada6
Author: AndreyIg <gnyiny@gmail.com>
Date:   Fri Jan 24 07:32:11 2020 -0800

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

commit 276c19b
Merge: 9b5a3f3 bc8e4be
Author: AndreyIg <gnyiny@gmail.com>
Date:   Mon Jan 20 14:32:44 2020 -0800

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

commit 8023485
Author: AndreyIg <gnyiny@gmail.com>
Date:   Mon Jan 20 14:24:12 2020 -0800

    fix setting supplemental logging for new table

commit f16f3a5
Merge: 91b00f8 9b5a3f3
Author: AndreyIg <gnyiny@gmail.com>
Date:   Wed Jan 15 13:44:36 2020 -0800

    Merge branch 'master' into DBZ-137_candidate_merge_branch

commit 9b5a3f3
Merge: 9b0ee98 f9de59c
Author: AndreyIg <gnyiny@gmail.com>
Date:   Wed Jan 15 13:41:38 2020 -0800

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

commit 91b00f8
Author: AndreyIg <gnyiny@gmail.com>
Date:   Mon Jan 6 16:09:22 2020 -0800

    DBZ-137_fix_oldest_scn_issue

commit 9b0ee98
Merge: 7ab9af3 0fe3cf3
Author: AndreyIg <gnyiny@gmail.com>
Date:   Fri Dec 27 11:55:19 2019 -0800

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

commit 7ab9af3
Merge: 90979c1 d8872ce
Author: AndreyIg <gnyiny@gmail.com>
Date:   Fri Dec 27 11:48:18 2019 -0800

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

commit 90979c1
Merge: d174eab 4086b3e
Author: AndreyIg <gnyiny@gmail.com>
Date:   Fri Dec 13 13:39:26 2019 -0800

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

commit d174eab
Merge: 0894de1 7e77a83
Author: AndreyIg <gnyiny@gmail.com>
Date:   Mon Dec 9 08:58:41 2019 -0800

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

commit 0894de1
Merge: 8353b85 12021bd
Author: AndreyIg <gnyiny@gmail.com>
Date:   Wed Nov 27 15:12:39 2019 -0800

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

commit 8353b85
Merge: c6f361f b69f88c
Author: AndreyIg <gnyiny@gmail.com>
Date:   Wed Nov 27 14:57:47 2019 -0800

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

commit c6f361f
Merge: 7b499a3 7c9497a
Author: AndreyIg <gnyiny@gmail.com>
Date:   Tue Nov 26 15:27:32 2019 -0800

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

commit 7b499a3
Merge: ff19baa 5be9ef5
Author: AndreyIg <gnyiny@gmail.com>
Date:   Fri Nov 22 14:09:47 2019 -0800

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

commit ff19baa
Merge: 7b0b476 0309d35
Author: AndreyIg <gnyiny@gmail.com>
Date:   Fri Sep 27 11:04:12 2019 -0700

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

commit 7b0b476
Merge: 5d76700 eaaddfb
Author: AndreyIg <gnyiny@gmail.com>
Date:   Thu Sep 5 15:52:31 2019 -0700

    ARGO-198431, new parser

commit 5d76700
Author: AndreyIg <gnyiny@gmail.com>
Date:   Thu Sep 5 15:01:49 2019 -0700

    ARGO-198431, new parser

commit 838f944
Merge: 9f00dfd 61d8afc
Author: AndreyIg <gnyiny@gmail.com>
Date:   Fri Aug 23 13:16:37 2019 -0700

    Merge branch 'master' of http://git.navis.lan/scm/n4fra/debezium

... and 2 more commits

debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/TransactionalBuffer.java

@@ -102,7 +102,7 @@ void registerCommitCallback(String transactionId, BigDecimal scn, Instant change
      * @return true if committed transaction is in the buffer
      */
     boolean commit(String transactionId, Timestamp timestamp, ChangeEventSource.ChangeEventSourceContext context, String debugMessage) {
-        BigDecimal smallestScn = transactions.isEmpty() ? null : calculateSmallestScn();
+        BigDecimal smallestScn = calculateSmallestScn();
         Transaction transaction = transactions.remove(transactionId);
         if (transaction == null) {
             return false;
@@ -173,12 +173,12 @@ void abandonLongTransactions(Long thresholdScn){
     }
 
     private BigDecimal calculateSmallestScn() {
-        BigDecimal scn = transactions.values()
+        BigDecimal scn = transactions.isEmpty() ? null : transactions.values()
                 .stream()
                 .map(transaction -> transaction.firstScn)
                 .min(BigDecimal::compareTo)
                 .orElseThrow(() -> new DataException("Cannot calculate smallest SCN"));
-        metrics.ifPresent(m -> m.setOldestScn(scn.longValue()));
+        metrics.ifPresent(m -> m.setOldestScn(scn == null ? null : scn.longValue()));
         return scn;
     }