Switch to use guava for best practices used in google.
Revert "Switch to use guava for best practices used in google."

This reverts commit f85e2f9459eb88c083fb7fb9c16716f53dcfa675.
Revert "Revert "Switch to use guava for best practices used in google.""

This reverts commit a2cf2c498da47a8e66445c438f5c323a3b8479b0.
add dependency for guava