Summary

Normalize entries read from unicast_hosts.txt before resolving file-based seed hosts.

Previously, FileBasedSeedHostsProvider passed each non-comment line from the file directly to the seed host resolver. This meant that an otherwise valid entry with leading or trailing whitespace, such as:

 192.168.0.1:9301 

was passed through unchanged and failed during transport address parsing. The same normalization gap also meant that blank lines and indented comments were treated as host entries.

This change strips each line before filtering and resolution, then ignores empty lines and comments after normalization.

Details

• Strip whitespace from each line read from unicast_hosts.txt.
• Ignore blank lines after stripping.
• Ignore comment lines after stripping, so indented comments are handled consistently.
• Add a focused test covering whitespace, blank lines, and indented comments in the file-based seed hosts provider.

Testing

The following tests were run locally:

./gradlew :server:test --tests org.elasticsearch.discovery.FileBasedSeedHostsProviderTests.testHostEntriesAreTrimmed
./gradlew :server:test --tests org.elasticsearch.discovery.FileBasedSeedHostsProviderTests
./gradlew :server:check

Both passed.