throw an exception when a new instance of a non-interface is passed to a builder.

Change-Id: I719a589f81feb779981b9097393b8d1b5f1d10f7
Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Minor JavaDoc cleanup

Change-Id: I88a234c655532bc69874ff4058142cdb3c7c9547