BUG-2383: lower default candidate allocation

Rather than allocating the default of 16 entries, we force the HashMap
to allocate a lower number of entries. While this is not a complete
solution, it lowers the memory overhead significantly.

Change-Id: Ic3afe36381930d567ee7523856b3d3959c013459
Signed-off-by: Robert Varga <rovarga@cisco.com>