Simple Plugin in Java for Gradle

build.gradle

// usage
ssh {
  // dsl form
  options {
    foo 'bar'
    name project.name
    flag(false) // also possible
  }

  // property form
  options.hello = 'world'
}

println ssh.options 
// { foo: "bar", name: "??", flag: false, hello: "world" } 

SSHPlugin.java

package org.company.gradle;

import groovy.lang.Closure;
import groovy.lang.MissingMethodException;
import org.gradle.api.Plugin;
import org.gradle.api.Project;

import java.util.HashMap;
import java.util.Map;

/**
 * Created by dteo on 18/07/2014.
 */
class SSHPlugin implements Plugin<Project> {

  @Override
  public void apply(Project project) {
    // this namespaces your configuration to ssh { }
    project.getExtensions().create("ssh", SSHConfiguration.class);
  }
}

// this will need to be an extension that you create in your plugin itself
class SSHConfiguration {
  private SSHOptions options = new SSHOptions();

  public SSHOptions getOptions() {
    return this.options;
  }

  // this will accept ssh { options { } }
  public void options(Closure closure) {
    closure.setResolveStrategy(Closure.DELEGATE_FIRST);
    closure.setDelegate(this.options);
    closure.call(this.options);
  }
}

class SSHOptions extends GroovyObjectSupport {
  private Map<String, Object> args = new HashMap<String,Object>();

  public String get(String name) {
    return this.args.get(name);
  }

  public Map<String, String> getAll() {
    return this.args;
  }

  public void set(String name, Object value) {
    if (value != null) {
      this.args.put(name, value.toString());
    } else {
      this.args.remove(name);
    }
  }


  public Object invokeMethod(String name, Object values) {
    Object[] args = (Object[]) values;

    if (args == null || args.length != 1) {
      throw new MissingMethodException(name, SSHOptions.class, args);
    }

    this.args.put(name, args[0]);
    return null;
  }
}

https://github.com/gradle/gradle/blob/master/subprojects/core/src/main/groovy/org/gradle/api/internal/artifacts/dsl/dependencies/DefaultDependencyHandler.java