fix(build): plain cli fails all queries on JDK 18+ — discard classless resolver-SPI registration (#171)

[fupelaqu]

Closes #171.

Root cause

dnsjava (transitive: dnsjava:dnsjava:3.6.1 ← org.apache.hadoop:hadoop-common:3.4.2 ← org.apache.hadoop:hadoop-client:3.4.2 ← softclient4es-core) ships META-INF/services/java.net.spi.InetAddressResolverProvider registering org.xbill.DNS.spi.DnsjavaInetAddressResolverProvider.

dnsjava 3.6.x is a multi-release jar: that provider class exists only under META-INF/versions/18/. The cli assembly merge strategy keeps every META-INF/services/* entry (MergeStrategy.concat) but discards everything else under META-INF/ — including the versioned class directories. The plain cli assemblies therefore ship the SPI registration without its class.

On JDK 18+ (JEP 418), the InetAddressResolver SPI is consulted on the first name resolution: the JVM tries to load the registered provider, fails with ServiceConfigurationError/ClassNotFoundException, and every query fails (reproduced on JDK 21 with the published 0.20.1 assemblies, found while validating PR #170). JDK 11/17 never consult the SPI, which is why this went unnoticed.

Fix

Add a more specific case before the services-concat line in the shared cliProject merge strategy (covers all cli assemblies — es6/7/8/9):

case PathList("META-INF", "services", "java.net.spi.InetAddressResolverProvider") =>
  MergeStrategy.discard

The class isn't shipped, so the registration must not be either — the JVM then falls back to the built-in resolver.

Evidence

Before (assembly built from main @ 12e60dd, same 0.20.1 layout as the published jar):

$ unzip -l softclient4es8-cli-0.20.1-assembly.jar | grep InetAddressResolverProvider
      53  META-INF/services/java.net.spi.InetAddressResolverProvider
$ unzip -p softclient4es8-cli-0.20.1-assembly.jar META-INF/services/java.net.spi.InetAddressResolverProvider
org.xbill.DNS.spi.DnsjavaInetAddressResolverProvider

…while org/xbill/DNS/spi/ in the same jar contains only DNSJavaNameService and DNSJavaNameServiceDescriptor — no DnsjavaInetAddressResolverProvider class (confirming the classless registration).

After (assembly rebuilt with the fix): the META-INF/services/java.net.spi.InetAddressResolverProvider entry is gone; all other service registrations (ExtensionSpi, ElasticClientSpi, Lucene codecs, jackson, slf4j, JLine providers, …) are intact.

Smoke tests (ES 8.18.3 single-node Docker, port 9271)

• JDK 21 (zulu 21.0.3): java -jar softclient4es8-cli-0.20.1-assembly.jar -p 9271 -c "SHOW TABLES" → ✅ No rows returned (250ms), metrics Success Rate: 100.0%, zero InetAddressResolver errors. Connecting to localhost proves the built-in resolver is used.
• Default JDK 11 (zulu 11.0.23): same command → ✅ No rows returned (244ms), Success Rate: 100.0% — no regression.

Versioning

No version bump — stays 0.20.1 and rides the 0.20.2 line via the epic PRs.

Refs #169 and PR #170 (where the bug was found).

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