Add references to Copernik.eu Log4j components (#3534)

This change adds references to the Log4j plugins from my personal "Extensions for Log4j and Tomcat" to the documentation.

Co-authored-by: Volkan Yazıcı <[email protected]>

Author: ppkarwasz

src/site/antora/modules/ROOT/pages/manual/lookups.adoc

@@ -966,7 +966,12 @@ include::partial$features/servlet-support.adoc[]
 [#third-party]
 == Third-party lookups
 
-The following additional lookups are available from third-party vendors:
+[IMPORTANT]
+====
+These lookups are provided by **third-party** vendors and are not maintained by the
+link:{logging-services-url}[Apache Logging Services]
+(Log4j, Log4cxx, Log4net) project.
+====
 
 [#KubernetesLookup]
 === Kubernetes Lookup
@@ -999,6 +1004,24 @@ The Spring Boot 3 Lookup conflicts with the <<#SpringBootLookup>>.
 If you are upgrading to Spring Boot 3, make sure to remove the latter from your classpath.
 ====
 
+[#TomcatLookup]
+=== Tomcat Lookup
+
+[cols="1h,4"]
+|===
+| Syntax
+|
+`tomcat:<key>`
+
+where `key` is one of the
+https://oss.copernik.eu/tomcat/3.x/components/log4j-tomcat#TomcatLookup-keys[supported Tomcat Lookup keys]
+| Dependency | https://oss.copernik.eu/tomcat/3.x/components/log4j-tomcat#installation[`eu.copernik:log4j-tomcat`]
+|===
+
+The Tomcat Lookup allows retrieving the names of the currently active Tomcat engine, host and application context.
+See
+https://oss.copernik.eu/tomcat/3.x/components/log4j-tomcat#TomcatLookup[Copernik.eu Tomcat Lookup documentation] for more details.
+
 [#extending]
 == Extending
 

src/site/antora/modules/ROOT/pages/manual/thread-context.adoc

@@ -159,7 +159,22 @@ You can provide a custom `ContextDataProvider` implementation as follows:
 ----
 META-INF/services/org.apache.logging.log4j.core.util.ContextDataProvider
 ----
-. Write the fully-qualified class name of your custom implementation (e.g., `com.mycompany.CustomContextDataProvider`) to the file created in the previous step
+. Write the fully-qualified class name of your custom implementation (e.g., `com.mycompany.CustomContextDataProvider`) to the file created in the previous step.
+
+==== Third-party custom thread context data providers
+
+[IMPORTANT]
+====
+These context data providers are supplied by **third-party** vendors and are not maintained by the
+link:{logging-services-url}[Apache Logging Services]
+(Log4j, Log4cxx, Log4net) project.
+====
+
+https://github.com/open-telemetry/opentelemetry-java-instrumentation/tree/main/instrumentation/log4j/log4j-context-data/log4j-context-data-2.17/library-autoconfigure[OpenTelemetry Context Data Provider]::
+Injects trace context data into log events.
+
+https://oss.copernik.eu/tomcat/3.x/components/log4j-tomcat#TomcatContextDataProvider[Copernik.eu Tomcat Context Data Provider]::
+Injects the name of the currently active Tomcat engine, host and web application into log events.
 
 [#custom-ThreadContextMap]
 === Custom thread context map

src/site/antora/modules/ROOT/partials/manual/systemproperties/properties-context-selector.adoc

@@ -51,4 +51,19 @@ link:../javadoc/log4j-core/org/apache/logging/log4j/core/osgi/BundleContextSelec
 Creates a separate logger context per OSGi bundle and synchronous loggers
 
 link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/JndiContextSelector.html[`org.apache.logging.log4j.core.selector.JndiContextSelector`]::
-Creates loggers contexts based on a JNDI lookup and synchronous loggers See xref:jakarta.adoc#jndi-configuration[Web application] for details.
+Creates loggers contexts based on a JNDI lookup and synchronous loggers See xref:jakarta.adoc#jndi-configuration[Web application] for details.
+
+There are also third-party context selector implementations:
+
+[IMPORTANT]
+====
+These context selectors are provided by **third-party** vendors and are not maintained by the
+link:{logging-services-url}[Apache Logging Services]
+(Log4j, Log4cxx, Log4net) project.
+====
+
+https://oss.copernik.eu/tomcat/3.x/components/log4j-tomcat#TomcatContextSelector[`eu.copernik.log4j.tomcat.TomcatContextSelector`]::
+Selects the currently active Tomcat web application and creates synchronous loggers.
+
+https://oss.copernik.eu/tomcat/3.x/components/log4j-tomcat#TomcatContextSelector[`eu.copernik.log4j.tomcat.TomcatAsyncContextSelector`]::
+Selects the currently active Tomcat web application and creates xref:manual/async.adoc[asynchronous loggers].