Add local decorating for customers using Log4j 2 with JsonTemplateLayout

[obenkenobi]

Overview

Adds local decorating (i.e. NR-LINKING metadata) to log4j 2 logs using JsonTemplateLayout such as shown configured in the XML snippet below:

	<Appenders>
		<Console name="Console" target="SYSTEM_OUT">
                         <JsonTemplateLayout eventTemplateUri="classpath:JsonLayout.json"/>
		</Console>
	</Appenders>

Example log without local decorating:

{
  "@timestamp": "2024-04-18T21:08:01.250Z",
  "log.level": "INFO",
  "process.thread.name": "http-nio-8081-exec-1",
  "log.logger": "org.springframework.samples.petclinic.system.WelcomeController",
  "message": "info bar"
}

Example log with local decorating:

{
  "@timestamp": "2024-04-18T21:08:01.250Z",
  "log.level": "INFO",
  "process.thread.name": "http-nio-8081-exec-1",
  "log.logger": "org.springframework.samples.petclinic.system.WelcomeController",
  "message": "info bar NR-LINKING|MzQ3Nzg3NHxBUE18QVBQTElDQVRJT058NTM4Mzc3ODY0|192.168.0.31|e0a726b1de7a78af9e74bfb042845180|3f4885dca4f83070|Petclinic+Log4j+Jsontemplatelayout+decorating|"
}

Related Github Issue

#1730

[jasonjkeller]

Couple of minor tweaks to be made but otherwise looks good.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 27 lines in your changes are missing coverage. Please review.

Project coverage is 70.69%. Comparing base (0e3a23f) to head (0117d92).
Report is 110 commits behind head on main.

Files	Patch %	Lines
.../com/newrelic/agent/bridge/logging/Log4jUtils.java	0.00%	27 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1866      +/-   ##
============================================
- Coverage     70.88%   70.69%   -0.19%     
+ Complexity     9974     9872     -102     
============================================
  Files           829      828       -1     
  Lines         39985    39832     -153     
  Branches       6058     6064       +6     
============================================
- Hits          28344    28161     -183     
- Misses         8915     8947      +32     
+ Partials       2726     2724       -2     

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