KT-16283 Maven compiler plugin warns, "Source root doesn't exist"

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

@@ -425,7 +425,8 @@ public abstract class KotlinCompileMojoBase<A extends CommonCompilerArguments> e
             if (sourceDir.exists()) {
                 sourceRoots.add(sourceDir);
             }
-            else {
+            // unfortunately there is no good way to detect generated sources directory so we simply keep hardcoded value
+            else if (!sourceDir.getPath().contains("generated-sources")) {
                 getLog().warn("Source root doesn't exist: " + sourceDir);
             }
         }