The usage of ‘Executing enviroments’ instead of plain JREs prohibits the use of JavaFX in gradle-generated eclipse projects since such execution enviroments contain access rules forbidding access to jars located in the ext folder of the JDK/JRE. In Java 8 the bundled JavaFX is installed inside this ext folder by default which renders it unusable.
The gradle eclipse plugin should allow some configuration to decide if an Execution Environment or a plain JRE should be written to the generated .classpath files.