builder helper maven plugin

maven/pom.xml

@@ -94,6 +94,24 @@
                     </filesets>
                 </configuration>
             </plugin>
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>build-helper-maven-plugin</artifactId>
+                <version>${maven.build.helper.version}</version>
+                <executions>
+                    <execution>
+                        <phase>generate-sources</phase>
+                        <goals>
+                            <goal>add-source</goal>
+                        </goals>
+                        <configuration>
+                            <sources>
+                                <source>src/main/another-src</source>
+                            </sources>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
         </plugins>
     </build>
 
@@ -102,6 +120,7 @@
         <maven.failsafe.version>2.21.0</maven.failsafe.version>
         <maven.verifier.version>1.1</maven.verifier.version>
         <maven.clean.version>3.0.0</maven.clean.version>
+        <maven.build.helper.version>3.0.0</maven.build.helper.version>
         <resources.name>Baeldung</resources.name>
     </properties>
 

maven/src/main/another-src/com/baeldung/maven/plugins/Foo.java

@@ -0,0 +1,10 @@
+package com.baeldung.maven.plugins;
+
+public class Foo {
+
+    public static String foo() {
+        return "foo";
+    }
+
+}
+

maven/src/main/java/com/baeldung/maven/plugins/MultipleSrcFolders.java

@@ -0,0 +1,9 @@
+package com.baeldung.maven.plugins;
+
+public class MultipleSrcFolders {
+
+    public static void callFoo() {
+        Foo.foo();
+    }
+
+}