Make doclava compatible with both JDK 8 and 11.

It seems that it might take several attemps to switch to JDK 11.
This patch makes it so doclava works with both JDK 8 and JDK 11 (when
passing in System.env.JAVA_TOOLS_JAR)

Test: tested building with both JDK 11 and JDK 8 locally.
Change-Id: Ia2128b175996be7a2d8d35eb92c1a1be4f13395c
1 file changed