build-plain.gradle

plugins {
    id 'org.kordamp.gradle.echo' version '0.40.0'
}

build-plugin.gradle

plugins {
    id 'org.kordamp.gradle.echo' version '0.40.0'
}

echo {
    message = 'Hello from task'
}

build-prop.gradle

plugins {
    id 'org.kordamp.gradle.echo' version '0.40.0'
}

project.ext.set('echo.message', 'Hello from build.gradle')

EchoTask.groovy

import groovy.transform.CompileStatic
import org.gradle.api.DefaultTask
import org.gradle.api.provider.Property
import org.gradle.api.provider.Provider
import org.gradle.api.tasks.Input
import org.gradle.api.tasks.Internal
import org.gradle.api.tasks.Optional
import org.gradle.api.tasks.TaskAction
import org.gradle.api.tasks.options.Option
import org.kordamp.gradle.property.SimpleStringState
import org.kordamp.gradle.property.StringState

@CompileStatic
class EchoTask extends DefaultTask {
    private final StringState message

    EchoTask() {
        message = SimpleStringState.of(this, 'echo.message', '')
    }

    @Option(option='echo-message', description = 'The message to write')
    void setMessage(String message) {
        getMessage().set(message)
    }

    @Internal
    Property<String> getMessage() {
        message.property
    }

    @Input
    @Optional
    Provider<String> getResolvedMessage() {
        message.provider
    }

    @TaskAction
    void echo() {
        println getResolvedMessage().get()
    }
}

pom-plain.xml

<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>
    <groupId>com.acme</groupId>
    <artifactId>sample</artifactId>
    <version>0.0.0-SNAPSHOT</version>

    <build>
        <plugins>
            <plugin>
                <groupId>com.github.ekryd.echo-maven-plugin</groupId>
                <artifactId>echo-maven-plugin</artifactId>
                <version>1.2.0</version>
                <inherited>false</inherited>
                <executions>
                    <execution>
                        <id>echo</id>
                        <goals>
                             <goal>echo</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

pom-plugin.xml

<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>
    <groupId>com.acme</groupId>
    <artifactId>sample</artifactId>
    <version>0.0.0-SNAPSHOT</version>

    <properties>
        <echo.message>Hello from pom.xml</echo.message>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>com.github.ekryd.echo-maven-plugin</groupId>
                <artifactId>echo-maven-plugin</artifactId>
                <version>1.2.0</version>
                <inherited>false</inherited>
                <executions>
                    <execution>
                        <id>echo</id>
                        <goals>
                             <goal>echo</goal>
                        </goals>
                        <configuration>
                            <message>hello</message>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

pom-prop.xml

<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>
    <groupId>com.acme</groupId>
    <artifactId>sample</artifactId>
    <version>0.0.0-SNAPSHOT</version>

    <properties>
        <echo.message>Hello from pom.xml</echo.message>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>com.github.ekryd.echo-maven-plugin</groupId>
                <artifactId>echo-maven-plugin</artifactId>
                <version>1.2.0</version>
                <inherited>false</inherited>
                <executions>
                    <execution>
                        <id>echo</id>
                        <goals>
                             <goal>echo</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>