Add Eclipse P2 repository customizable keystore/truststore configuration

[PeterTranHuynh]

If you are submitting a bug, please include the following:

• summary of problem
• Gradle or Maven version
• spotless version
• operating system and version
• copy-paste your full Spotless configuration block(s), and a link to a public git repo that reproduces the problem if possible
• copy-paste the full content of any console errors emitted by gradlew spotless[Apply/Check] --stacktrace

If you're just submitting a feature request or question, no need for the above.

• Summary:
  Hello, I was running into a situation where I couldn't find any configuration to designate a specific truststore, keystore, and keystore password path for a P2 Mirror host for my eclipse code styles. I'm running on a closed off system during my pipeline builds, which requires a P2 mirror as the normal eclipse one is unreachable. The mirror I can reach requires some SSL handshake with the proper certificate from some custom CA. I wasn't able to figure out a way to point the spotless check to a JKS or P12 I generated with my pipeline's cert or point to a specific cacert store either. Is there proper documentation on this that I potentially missed somewhere?

• Gradle Version: 8.7

• Spotless Version: 6.25.0

• OS: RHEL 9

• Configuration:

  spotless {
      java {
          target fileTree('.') {
              include '**/*.java'
              exclude '**/build/**'
          }
          eclipse()
              .withP2Mirror(['https://download.eclipse.org':'https://mirror_p2_host'])
              .configFile("$rootDir/eclipse-code-style.xml")
          removeUnusedImports()
          formatAnnotations()
          indentWithSpace(4)
          trimTrailingWhitespace()
          endWithNewline()
          toggleOffOn()
          licenseHeaderFile("$rootDir/license")
      }
  }

• Related Error:

  > Could not determine the dependencies of task ':spotlessCheck'
  > Could not create task ':spotlessJavaCheck'
  > Could not create task ':spotlessJava'
  > java.io.IOException: Failed to load eclipse jdt formatter: java.lang.RuntimeException: javax.net.ssl.SSLHandshakeException: Received fatal alert: certificate_required