Make KDoc generate documentation on red code

KDoc is not a compiler, so it should not care whether or not the code is valid.
Therefore suppress the compiler's exit code, errors and warnings in KDoc plugin

libraries/tools/kotlin-maven-plugin/src/main/java/org/jetbrains/kotlin/maven/KotlinCompileMojoBase.java

@@ -206,7 +206,7 @@ public abstract class KotlinCompileMojoBase extends AbstractMojo {
             }
         };
 
-        final ExitCode exitCode = compiler.exec(messageCollector, arguments);
+        final ExitCode exitCode = executeCompiler(compiler, arguments, messageCollector);
 
         switch (exitCode) {
             case COMPILATION_ERROR:
@@ -258,6 +258,15 @@ public abstract class KotlinCompileMojoBase extends AbstractMojo {
         return new K2JVMCompilerArguments();
     }
 
+    @NotNull
+    protected ExitCode executeCompiler(
+            @NotNull CLICompiler compiler,
+            @NotNull CommonCompilerArguments arguments,
+            @NotNull MessageCollector messageCollector
+    ) {
+        return compiler.exec(messageCollector, arguments);
+    }
+
     /**
      * Derived classes can register custom plugins or configurations
      */