[Gradle] Generate Javadoc including JavaScript in Java 1.8.0_121 or later

This is for those who have set JavaScript in Gradle's javadoc.options.bottom etc.

In Java 1.8.0_121, the javadoc command no longer allows JavaScript by default. http://www.oracle.com/technetwork/java/javase/8u121-relnotes-3315208.html

The javadoc tool will now reject any occurrences of JavaScript code in the javadoc documentation comments and command-line options, unless the command-line option, --allow-script-in-comments is specified.

I get an error when I run the javadoc task.

$ ./gradlew javadoc
[snip]
:javadoc
javadoc: error - Argument for -bottom contains JavaScript.
Use --allow-script-in-comments to allow use of JavaScript.
1 error
:javadoc FAILED

FAILURE: Build failed with an exception.

To enable JavaScript, add the --allow-script-in-comments option as described in the error message above.

build.gradle

javadoc.options {
    def v = JavaVersion.current()
    def g = System.properties['java.version'] =~ /\d+/
    addBooleanOption '-allow-script-in-comments', v.java9Compatible || v.majorVersion == '8' && g.size() == 4 && ((g[2] as int) > 0 || (g[3] as int) >= 121)
}

For the first argument of ʻaddBooleanOption, specify the option without the leading-. In the second argument, specify the boolean` value of whether to set the option. If you specify this option in a Java environment of 1.8.0_121 or earlier, an error will occur when executing the javadoc task, so the Java version is used to determine whether to set the option.

that's all.

reference

Gradle issue https://github.com/gradle/gradle/issues/1393 Implementation of javadoc.options.addBooleanOption https://github.com/gradle/gradle/blob/master/subprojects/language-java/src/main/java/org/gradle/external/javadoc/CoreJavadocOptions.java https://github.com/gradle/gradle/blob/master/subprojects/language-java/src/main/java/org/gradle/external/javadoc/internal/JavadocOptionFile.java https://github.com/gradle/gradle/blob/master/subprojects/language-java/src/main/java/org/gradle/external/javadoc/internal/BooleanJavadocOptionFileOption.java