AccountCache#get returns an empty AccountState to represent a missing
account and hence returns never null. SubmitStrategyOp#getByAccountName
wants to handle the missing account case, but it expected
AccountCache#get to return null in this case which is wrong. Instead use
AccountCache#maybeGet and handle the missing account case correctly.
Change-Id: Ibc6d3dea90f2b37c4b1f1db9393dfdee16b354a6
Signed-off-by: Edwin Kempin <ekempin@google.com>