build.gradle

subprojects {
  apply plugin: 'java'
  apply plugin: 'war'
  group = 'com.johnathangilday'
  version = '1.0'
  repositories {
    mavenCentral()
  }
}

configure(subprojects.findAll { it.name != 'app' }) {
  // extract variation encoded in the project name
  def variation = project.name.substring(rootProject.name.length() + 1)
  dependencies {
    // use the variation to specify the servlet-api version
    compile "javax.servlet:servlet-api:${variation}"
    // include the app project where the web application servlet is defined
    compile project(':app')
  }
}

project('app') {
  dependencies {
    // the app project uses a version of the servlet-api
    // compileOnly because we do not want to include this as a transitive dependency - the subprojects
    // will bring their own version of the servlet-api
    compileOnly 'javax.servlet:servlet-api:2.5'
  }
}