fix(cloud-logging): removing Logstash dependencies, using Cloud Logging Logback

[Kef131]

Description

Fixes b/362827197

Updates the Google Cloud Run manual logging sample for Java to use the officially recommended Google Cloud Logging Logback Appender (google-cloud-logging-logback) instead of the third-party logstash-logback-encoder plugin.

Main changes:

• Removed Logstash dependency: Removed the logstash-logback-encoder plugin alongside custom Logstash kv() key-value parameters used to write JSON structured logs.
• Adopted native Google Cloud Logging: Switched to the google-cloud-logging-logback plugin, which natively supports structured logging and can output directly to standard output via <redirectToStdout>true</redirectToStdout>.
• Updated Dependency Management:
  • Added libraries-bom under <dependencyManagement> to manage Google Cloud library versions.
  • Replaced logstash-logback-encoder with google-cloud-logging-logback.
  • Kept logback-classic and logback-core aligned at version 1.4.14 to ensure seamless SLF4J 2.x provider binding.
• Updated Logback Configuration: Replaced the Logstash appender and custom JSON encoder field filters with Google's official LoggingAppender, configured with <redirectToStdout>true</redirectToStdout>.
• Adjusted Tests:
  • Adjusted the test initialization so that redirection to standard output happens in @BeforeClass before spark-java loads the class-level static logger.
  • Updated test assertions to check for "INFO" instead of "NOTICE".

Checklist

• I have followed Sample Format Guide
• pom.xml parent set to latest shared-configuration
• Appropriate changes to README are included in PR
• These samples need a new API enabled in testing projects to pass (None)
• These samples need a new/updated env vars in testing projects set to pass (None)
• Tests pass: mvn clean verify required
• Lint passes: mvn -P lint checkstyle:check required
• Static Analysis: mvn -P lint clean compile pmd:cpd-check spotbugs:check advisory only
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

[gemini-code-assist]

Code Review

This pull request updates the manual logging implementation in the Cloud Run Java sample to use Google Cloud Logging Logback integration instead of Logstash. Specifically, it replaces logstash-logback-encoder with google-cloud-logging-logback, migrates structured logging from StructuredArguments.kv to SLF4J's Mapped Diagnostic Context (MDC), and updates the logback.xml configuration to use LoggingAppender redirecting to stdout. Additionally, test setup has been refactored to handle output streams statically, and the test assertions were updated to match the new INFO log level. I have no feedback to provide as the changes are clean and correct.

[Kef131]

/gemini review

[gemini-code-assist]

Code Review

This pull request migrates the manual logging implementation from using Logstash Logback encoder to the Google Cloud Logging Logback appender. It replaces structured logging via key-value pairs with SLF4J's Mapped Diagnostic Context (MDC) and updates the test assertions accordingly. A review comment suggests restoring the original System.out stream in @AfterClass to prevent console output pollution for other tests.

[Kef131]

Important to mention that the severity on SLF4J logger object is given by the logged method (e.g., logger.info() maps to INFO, logger.warn() to WARNING, logger.error() to ERROR).