PHPCS: fix up the code base [31] - rename a private property
PHPCS: fix up the code base [31] - rename a private property

Property names should be in `snake_case`.

As this is a private property, it can be safely renamed without BC.

rodrigoprimo/wp-cli,trepmal/wp-cli,aaemnnosttv/wp-cli,aaemnnosttv/wp-cli,aaemnnosttv/wp-cli,trepmal/wp-cli,rodrigoprimo/wp-cli,trepmal/wp-cli,rodrigoprimo/wp-cli