Compile main code with default java compiler and compile test code with eclipse-groovy compiler, with unit tests and integration tests in separate directories

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <groupId>eu.seropian.maven</groupId>
    <artifactId>demo</artifactId>
    <name>root pom</name>
    <packaging>pom</packaging>
    <version>1.0.0-SNAPSHOT</version>

    <pluginRepositories>
        <pluginRepository>
            <id>bintray</id>
            <name>Groovy Bintray</name>
            <url>https://dl.bintray.com/groovy/maven</url>
            <releases>
                <updatePolicy>never</updatePolicy>
            </releases>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </pluginRepository>
    </pluginRepositories>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.7.0</version>
                <inherited>true</inherited>
                <executions>
                    <execution>
                        <id>default-testCompile</id>
                        <phase>test-compile</phase>
                        <goals>
                            <goal>testCompile</goal>
                        </goals>
                        <configuration>
                            <fork>true</fork>
                            <!--<compilerVersion>1.8</compilerVersion>-->
                            <source>${java.version}</source>
                            <target>${java.version}</target>
                            <encoding>${project.build.sourceEncoding}</encoding>
                            <showWarnings>true</showWarnings>
                            <showDeprecation>true</showDeprecation>
                            <debug>true</debug>
                            <optimize>false</optimize>
                            <verbose>true</verbose>
                            <compilerId>groovy-eclipse-compiler</compilerId>
                        </configuration>
                    </execution>
                    <execution>
                        <id>integration-testCompile</id>
                        <phase>pre-integration-test</phase>
                        <goals>
                            <goal>testCompile</goal>
                        </goals>
                        <configuration>
                            <fork>true</fork>
                            <!--<compilerVersion>1.8</compilerVersion>-->
                            <source>${java.version}</source>
                            <target>${java.version}</target>
                            <encoding>${project.build.sourceEncoding}</encoding>
                            <showWarnings>true</showWarnings>
                            <showDeprecation>true</showDeprecation>
                            <debug>true</debug>
                            <optimize>false</optimize>
                            <verbose>true</verbose>
                            <compilerId>groovy-eclipse-compiler</compilerId>
                            <compileSourceRoots>
                                <compileSourceRoot>src/test/integration/java</compileSourceRoot>
                            </compileSourceRoots>
                            <outputDirectory>
                                ${project.build.directory}/integration-test-classes
                            </outputDirectory>
                        </configuration>
                    </execution>
                </executions>
                <dependencies>
                    <dependency>
                        <groupId>org.codehaus.groovy</groupId>
                        <artifactId>groovy-eclipse-compiler</artifactId>
                        <version>2.9.2-04</version>
                    </dependency>
                    <dependency>
                        <groupId>org.codehaus.groovy</groupId>
                        <artifactId>groovy-eclipse-batch</artifactId>
                        <version>2.4.13-02</version>
                    </dependency>
                </dependencies>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.21.0</version>
                <inherited>true</inherited>
                <configuration>
                    <forkMode>once</forkMode>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-failsafe-plugin</artifactId>
                <version>2.21.0</version>
                <inherited>true</inherited>
                <extensions>true</extensions>
                <executions>
                    <execution>
                        <id>integration-test</id>
                        <phase>integration-test</phase>
                        <goals>
                            <goal>integration-test</goal>
                        </goals>
                        <configuration>
                            <testSourceDirectory>src/test/integration/java</testSourceDirectory>
                            <testClassesDirectory>
                                ${project.build.directory}/integration-test-classes
                            </testClassesDirectory>
                            <includes>*</includes>
                        </configuration>
                    </execution>
                    <execution>
                        <id>verify</id>
                        <phase>verify</phase>
                        <goals>
                            <goal>verify</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <forkMode>once</forkMode>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-resources-plugin</artifactId>
                <version>3.0.2</version>
                <inherited>true</inherited>
            </plugin>
        </plugins>
    </build>