Fix some Javadoc errors reported when compiling with Java 8.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/dbcp/trunk@1631437 13f79535-47bb-0310-9956-ffa450edef68
Missed a Java8 Javadoc issue in previous commit

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/dbcp/trunk@1631450 13f79535-47bb-0310-9956-ffa450edef68