/*
 * Copyright (C) 2021 DiffPlug
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.diffplug.gradle.eclipserunner;


import java.util.regex.Matcher;
import java.util.regex.Pattern;

class JreVersion {
	public static int thisVm() {
		String jre = System.getProperty("java.version");
		if (jre.startsWith("1.8")) {
			return 8;
		} else {
			Matcher matcher = Pattern.compile("(\\d+)").matcher(jre);
			if (!matcher.find()) {
				throw new IllegalArgumentException("Expected " + jre + " to start with an integer");
			}
			int version = Integer.parseInt(matcher.group(1));
			if (version <= 8) {
				throw new IllegalArgumentException("Expected " + jre + " to start with an integer greater than 8");
			}
			return version;
		}
	}
}

Add the ability to calculate JRE version.
Add the ability to calculate JRE version.