A modern programming language that makes developers happier.

kotlinlang

For a mixed Java and Kotlin project (using Maven), is it a better practice to:
    1) use separate `src/main/kotlin` and `src/main/java` source directories; 
    2) use a single source directory (and mix Kotlin &amp; java source files); or 
    3) there's no technical "driver" for one over the other and is a matter of preference
I only ask because the "Convert Java to Kotlin" action in IDEA puts the new Kotlin file in the Java source. So I wasn't sure if that was a "limitation" of the plugin action, or a desired behavior.