gistfile1.xml

<plugin>
	<groupId>org.codehaus.mojo</groupId>
	<artifactId>build-helper-maven-plugin</artifactId>
	<version>1.8</version>
	<executions>
		<execution>
			<phase>generate-sources</phase>
			<goals>
				<goal>add-source</goal>
			</goals>
			<configuration>
				<sources>
					<source>target/generated-sources/antlr4</source>
				</sources>
			</configuration>
		</execution>
	</executions>
</plugin>