Hi, just wanted to let you know my WordFence alerted me to a modified file in W3 Cache and showed the differences in Root_Environment .php file. Around line 224 looks like a typo in the code.

Original:
if ( ! empty( $license_key ) ) {

Modified February 7 (probably an update because all files say February 7):
if ( ! emtpy( $license_key ) ) {

If you are not seeing it, the word empty is mis-spelled in the most recent update.