Building a JavaFX application

Question

In Java 8 times I created a JavaFX application which I now wanted to port and build with Java 11.

First thing I did was creating a module-info.java and adding the required libraries.

Than I added OpenJFX dependencies to gradle.build:

sourceCompatibility = JavaVersion.VERSION_11
targetCompatibility = JavaVersion.VERSION_11

repositories {
  mavenCentral()
}

dependencies {
  compile 'org.openjfx:javafx:11.0.1'
  compile 'org.openjfx:javafx-base:11.0.1'
  compile 'org.openjfx:javafx-controls:11.0.1'
}

After refreshing Gradle, I still got errors like Cannot resolve Symbol 'javafx.beans.property.StringProperty'.

Next thing I tried to modify the module-info.java like that:

module foo {
  requires org.apache.commons.lang3;  // another external dependency
  requires javafx.base;
  requires javafx.controls;
}

But this did not change anything, it I rather get the error Module not found: javafx.base.

Could anyone point out what it is I am doing wrong?