Use Classgraph to Import Unknown Packages Not Yet Loaded

[nbauernfeind]

Fixes #1129.

[devinrsmith]

I like classgraph. We need to decide if this additional dependency is worth it. It doesn't have any external dependencies itself, which is nice.

I'd bump to the latest version.

[nbauernfeind]

I've bumped. I'd be interested in any other approach you have in mind. The reported bug is an annoying thing for the user to need to handle.

Maybe we should make groovy-support an extension?

[devinrsmith]

LGTM, one more point.

[devinrsmith]

Let's check w/ @rcaudy too

[nbauernfeind]

I can verify that class graph does not initialize any classes until they are actually loaded:

package io.deephaven.server;

public class TestStatic {
    static {
        System.out.println("Initializing TestStatic");
    }
}

I ran three commands one at a time, in this order:

import io.deephaven.server.barrage.*

import io.deephaven.server.*

import io.deephaven.server.TestStatic

Only the last of which printed my static initializer:

Initializing TestStatic

[nbauernfeind]

Including Ryan's request to avoid initializing the class, this TestStatic class is not initialized until after it is actually used.

Results in no output:

import io.deephaven.server.TestStatic

Can finish loading the class like so:

println(TestStatic.class.toString())

Yields:

- Initializing TestStatic
- class io.deephaven.server.TestStatic