diff --git a/src/main/java/org/apache/maven/plugin/compiler/CompilerMojo.java b/src/main/java/org/apache/maven/plugin/compiler/CompilerMojo.java
index 306ac5933..31c5a86fa 100644
--- a/src/main/java/org/apache/maven/plugin/compiler/CompilerMojo.java
+++ b/src/main/java/org/apache/maven/plugin/compiler/CompilerMojo.java
@@ -83,6 +83,11 @@ public class CompilerMojo extends AbstractCompilerMojo {
 
     /**
      * A set of exclusion filters for the compiler.
+     * Excluding a source file only prevents the plugin from passing it explicitly to the compiler.
+     * The compiler may still find it on the source path and generate a class file for it.
+     * This can happen with {@code module-info.java}.
+     *
+     * @see #implicit
      */
     @Parameter
     protected Set<String> excludes;
diff --git a/src/main/java/org/apache/maven/plugin/compiler/TestCompilerMojo.java b/src/main/java/org/apache/maven/plugin/compiler/TestCompilerMojo.java
index 1cdc33633..b983b67a4 100644
--- a/src/main/java/org/apache/maven/plugin/compiler/TestCompilerMojo.java
+++ b/src/main/java/org/apache/maven/plugin/compiler/TestCompilerMojo.java
@@ -80,8 +80,12 @@ public class TestCompilerMojo extends AbstractCompilerMojo {
 
     /**
      * A set of exclusion filters for the compiler.
+     * Excluding a source file only prevents the plugin from passing it explicitly to the compiler.
+     * The compiler may still find it on the source path and generate a class file for it.
+     * This can happen with {@code module-info.java}.
      *
      * @see CompilerMojo#excludes
+     * @see #implicit
      */
     @Parameter
     protected Set<String> testExcludes;