Wildcard imports of built-in packages don't work

[rbasralian]

A wildcard import like:

import java.util.concurrent.*

throws:

com.illumon.iris.controller.exception.ScriptException: java.lang.RuntimeException: Attempting to import a path that does not exist: import java.util.concurrent.*;
	at io.deephaven.engine.util.GroovyDeephavenSession.updateScriptImports(GroovyDeephavenSession.java:582)
	at io.deephaven.engine.util.GroovyDeephavenSession.grepScriptImports(GroovyDeephavenSession.java:592)
	at io.deephaven.engine.util.GroovyDeephavenSession.evaluate(GroovyDeephavenSession.java:307)
	at io.deephaven.engine.util.AbstractScriptSession.lambda$evaluateScript$0(AbstractScriptSession.java:147)
	at io.deephaven.engine.context.ExecutionContext.lambda$apply$0(ExecutionContext.java:149)
	at io.deephaven.engine.context.ExecutionContext.apply(ExecutionContext.java:160)
	at io.deephaven.engine.context.ExecutionContext.apply(ExecutionContext.java:148)

This is basically because groovyShell.getClassLoader().getDefinedPackage("java.util.concurrent") returns null. (Using .getPackage(), which is deprecated, does work. It eventually calls jdk.internal.loader.BootLoader.getDefinedPackage())

[rcaudy]

Eww. Why do we still have things that grep script imports?

Regardless, I'm pretty confident that getPackage is internally racy and unreliable.

[niloc132]

ClassLoader.getDefinedPackage is expected to return null in these cases for the first import - we have a unit test that validates that null must be returned before trying to run a wildcard import:

deephaven-core/engine/table/src/test/java/io/deephaven/engine/util/scripts/TestGroovyDeephavenSession.java

Lines 131 to 140 in e4d69fd

	@Test
	public void testUnloadedWildcardPackageImport() {
	// it's unlikely we have loaded anything from this groovy package
	final String packageString = "groovy.time";
	if (this.getClass().getClassLoader().getDefinedPackage(packageString) != null) {
	Assert.fail("Package '" + packageString + "' is already loaded, test with a more obscure package.");
	}
	session.evaluateScript("import " + packageString + ".*").throwIfError();
	}

However, changing groovy.time to java.util.concurrent (or java.util) in that test produces a failure, as this bug describes (contrast with io.deephaven.engine.util, which will not return null from that test on line 136, and so the test cannot run).

In GroovyDeephavenSession.createClassImport, after getDefinedPackage fails, ClassGraph is used to look up the class. ClassGraph has a specific config that must be applied to be able to scan system modules/packages - enabling that appears to resolve this.