Consider the following:

package test24
import java.text.NumberFormat
class Test24 {
	static main(args) {
			NumberFormat.|
			Set<Integer> s = []
	}
}

Invoke code assist at "|" with Ctrl+Space and start typing getN: getNumberInstance is not shown as a suggestion. Press Esc and Ctrl+Space again: voilà!
If you remove the following line (Set<Integer> s = []), code assist works fine from the beginning.