Fix documentation of logger generator

The documentation for the code generators are replaced with a link to the Apache Log4j Transform project documentation.

Author: ppkarwasz

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

@@ -218,106 +218,4 @@ and `error()` methods.
 [#CustomLoggers]
 == Generating Source Code for a Custom Logger Wrapper
 
-Common Log4j usage is to get an instance of the `Logger` interface from
-the `LogManager` and call the methods on this interface. However, the
-custom log Levels are not known in advance, so Log4j cannot provide an
-interface with convenience methods for these custom log Levels.
-
-To solve this, Log4j ships with a tool that generates source code for a
-Logger wrapper. The generated wrapper class has convenience methods for
-each custom log level, making custom levels just as easy to use as the
-built-in levels.
-
-There are two flavors of wrappers: ones that _*extend*_ the Logger API
-(adding methods to the built-in levels) and ones that _*customize*_ the
-Logger API (replacing the built-in methods).
-
-When generating the source code for a wrapper class, you need to
-specify:
-
-* the fully qualified name of the class to generate
-* the list of custom levels to support and their `intLevel` relative
-strength
-* whether to extend `Logger` (and keep the existing built-in methods) or
-have only methods for the custom log levels
-
-You would then include the generated source code in the project where
-you want to use custom log levels.
-
-[#ExampleUsage]
-== Example Usage of a Generated Logger Wrapper
-
-Here is an example of how one would use a generated logger wrapper with
-custom levels DIAG, NOTICE and VERBOSE:
-
-[source,java]
-----
-// ExtLogger is a generated logger wrapper
-import com.mycompany.myproject.ExtLogger;
-
-public class MyService {
-    // instead of Logger logger = LogManager.getLogger(MyService.class):
-    private static final ExtLogger logger = ExtLogger.create(MyService.class);
-
-    public void demoExtendedLogger() {
-        // ...
-        logger.trace("the built-in TRACE level");
-        logger.verbose("a custom level: a VERBOSE message");
-        logger.debug("the built-in DEBUG level");
-        logger.notice("a custom level: a NOTICE message");
-        logger.info("the built-in INFO level");
-        logger.diag("a custom level: a DIAG message");
-        logger.warn("the built-in WARN level");
-        logger.error("the built-in ERROR level");
-        logger.fatal("the built-in FATAL level");
-        logger.notice("java 8 lambda expression only executed if NOTICE is enabled: {}", () -> someMethod());
-        // ...
-    }
-    ...
-}
-----
-
-[#CodeGen]
-== Generating Extended Loggers
-
-Use the following command to generate a logger wrapper that adds methods
-to the built-in ones:
-
-[source,sh,subs="attributes"]
-----
-java -cp log4j-core-{log4j-core-version}.jar org.apache.logging.log4j.core.tools.ExtendedLoggerGenerator \
-        com.mycomp.ExtLogger DIAG=350 NOTICE=450 VERBOSE=550 > com/mycomp/ExtLogger.java
-----
-
-This will generate source code for a logger wrapper that has the
-convenience methods for the built-in levels _as well as_ the specified
-custom levels. The tool prints the generated source code to the console.
-By appending " > _filename_" the output can be redirected to a file.
-
-NOTE: Prior to log4j-2.9, this tool was an inner class
-`Generate$ExtendedLogger`. +
-Under the bash shell on Unix/Mac/Linux the dollar character $ needs to
-be escaped, so the class name should be between single quotes
-'org.apache.logging.log4j.core.tools.Generate$ExtendedLogger’.
-
-== Generating Custom Loggers
-
-Use the following command to generate a logger wrapper that hides the
-built-in levels and has only custom levels:
-
-[source,sh,subs="attributes"]
-----
-java -cp log4j-core-{log4j-core-version}.jar org.apache.logging.log4j.core.tools.CustomLoggerGenerator \
-        com.mycomp.MyLogger DEFCON1=350 DEFCON2=450 DEFCON3=550 > com/mycomp/MyLogger.java
-----
-
-This will generate source code for a logger wrapper that _only_ has
-convenience methods for the specified custom levels, _not_ for the
-built-in levels. The tool prints the generated source code to the
-console. By appending " > _filename_" the output can be redirected to a
-file.
-
-NOTE: Prior to log4j-2.9, this tool was an inner class `Generate$ExtendedLogger`.
-Under the bash shell on Unix/Mac/Linux the dollar character $ needs to
-be escaped, so the class name should be between single quotes
-'org.apache.logging.log4j.core.tools.Generate$CustomLogger’.
+In order to automatically generate custom logger wrappers, see the https://logging.apache.org/log4j/transform/latest/#log4j-codegen'[Apache Log4j code generator].