Update codebase to follow style guide conventions

[Copilot]

This PR updates the codebase to align with the conventions outlined in docs/style-guide.md. The changes are minimal and focused on improving code consistency without affecting functionality.

Changes Made

Class Design

• Added final keyword to 6 public API classes that implement interfaces (e.g., GCPResourceProvider, CloudFoundryResourceProvider, BaggageSpanProcessor)
• These classes were not intended for inheritance, making them final clarifies the design intent

Method Parameters

• Removed incorrect final keyword from 5 method parameters and loop variables in GroovyRunner.java
• The style guide explicitly states that method parameters and local variables should never be declared final

Test Assertions

• Converted JUnit assertions to AssertJ in 3 test files for better error messages:
  • OtelTraceStateTest (consistent56 package)
  • ConsistentSamplerTest
  • ConsistentProbabilityBasedSamplerTest
• Changed assertEquals() calls to assertThat().isEqualTo() and assertTrue() to assertThat().isTrue()

SPI Registration

• Added @AutoService annotations to 3 SPI implementations to automatically generate service registration files
• Removed manual META-INF/services/ files that are now generated at compile time
• Added required auto-service dependencies to affected modules

Verification

All changes have been tested:

• Code compiles successfully
• Tests pass without modification
• Service registration works correctly with @AutoService
• No breaking changes to public APIs

These updates improve code maintainability and consistency while following established OpenTelemetry Java conventions.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• scans-in.gradle.com
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-opens=java.base/java.nio.charset=ALL-UNNAMED --add-opens=java.base/java.net=ALL-UNNAMED --add-opens=java.base/java.util.concurrent=ALL-UNNAMED --add-opens=java.base/java.util.concurrent.atomic=ALL-UNNAMED --add-opens=java.xml/javax.xml.namespace=ALL-UNNAMED -XX:MaxMetaspaceSize=512m -Dfile.encoding=UTF-8 -Duser.country -Duser.language=en -Duser.variant -cp /home/REDACTED/.gradle/wrapper/dists/gradle-9.0.0-bin/d6wjpkvcgsg3oed0qlfss3wgl/gradle-9.0.0/lib/gradle-daemon-main-9.0.0.jar -javaagent:/home/REDACTED/.gradle/wrapper/dists/gradle-9.0.0-bin/d6wjpkvcgsg3oed0qlfss3wgl/gradle-9.0.0/lib/agents/gradle-instrumentation-agent-9.0.0.jar org.gradle.launcher.daemon.bootstrap.GradleDaemon 9.0.0 (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.