Recover the offset from HDFS, even if topic name is not present in storage path

[hariprasad-k]

Problem

Exactly-once semantics should also work without topic name included in the path.

Solution

The function that recover offsets from file names will use the correct path by taking into account a new configuration flag path_include_topicname introduced with confluentinc/kafka-connect-storage-common#126.

Further, the backward compatibility of appending the topic name is retained by default value true for path_include_topicname.

Does this solution apply anywhere else?

• [x] yes
• [ ] no

If yes, where?

This change is necessary to retain EOS semantics to support flexible storage partitioning scheme as proposed here: confluentinc/kafka-connect-storage-common#126

Test Strategy

Testing done:

• [x] Unit tests
• [x] Integration tests
• [ ] System tests
• [ ] Manual tests

Release Plan

[ghost]

@confluentinc It looks like @hariprasad-k just signed our Contributor License Agreement. :+1:

Always at your service,

clabot

[hariprasad-k]

Fixes #515

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