#148 #6 Update to latest log4j2 version and improve Log Configuration

[ndoschek]

148 Update to org.apache.logging.log4j version to 2.17.1

• consumes from intermediate orbit build - desired version will be available with 2022-03 release (follow-up: #166)
• Migrate to log4j v2

144 Upgrade to stable Javalin 4 version

• Upgrade to Javalin 4.3.0
  • Adapt to API changes
  • JavalinJackson is no Singleton anymore - therefore we consume the ObjectMapper via the existing ProviderDefaults class instead

6 Improve Log Configuration

• Unify logging mechanisms and use log4j-slf4j-impl to redirect Javalin's slf4j logging to Log4j2 logger (as Log4J offers more flexible configuration)
• Introduce log4j2.xml configuration files
  • Default configuration on level 'debug' and prints fatal/error to stderr, all levels above to stdout
  • Add configuration files to classpath
• Introduce new CLI arguments to declare custom log configuration file and to enable extensive developer request/response logging
• Remove errorsOnly CLI argument
• Use complete classname for loggers - in default logging configuration it is configured to only use simple class name

General

• Update org.eclipse.emfcloud.emfjson-jackson version to 2.0.0
• Fix build warnings and correct output folders in build.properties
• Add ping option to ExampleModelServerClient
• Upgrade maven dependencies to match target platform
  • Update dependency jars in org.eclipse.emfcloud.modelserver.lib
• Update README (and resolve some markdownlint warnings)

Fixes #6 Fixes #144 Fixes #148

[ndoschek]

Thanks for your review Martin! Yes indeed, we never inject it at the moment, only use the static access in static methods of JsonCodec or the util ContextRequest. Opening an issue to investigate that further would be a good idea imo. Thanks!