Add missing Javadoc tags.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/exec/trunk@1636064 13f79535-47bb-0310-9956-ffa450edef68
Typo.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/exec/trunk@1636065 13f79535-47bb-0310-9956-ffa450edef68