Change key-source separator in TimeInStateHelper

The injectOption (tradefed functions) already used ":" and "=" as
separators, we need to change the separator to another character ("@").

This will also add a checking whether the source file exists or not
during setUp().

Test: TimeInStateHelperTest and TimeInStateListenerTest
Bug: 209531420
Change-Id: I4731590df75a398a664a76da1769d80ac55f5f29
4 files changed
tree: 12070787648b08f558a2d3fc519e5675cf57efe2
  1. build/
  2. docs/
  3. emu_test/
  4. libraries/
  5. scripts/
  6. tests/
  7. utils/
  8. PREUPLOAD.cfg