Glow lichens can spread into spawn protection

The Bug:

Glow lichens can spread into spawn protection.

Steps to Reproduce:

• Start a server, join it, give operator permissions to yourself, and switch into creative mode.
• Set the world spawn to your current location and locate the edge of spawn protection.
• Place a glow lichen adjacent to, but not inside of spawn protection.
• Obtain some bone meal and switch into survival mode.
• Remove your operator permissions, and grant anyone else with them in order to activate spawn protection.
• Apply several amounts of bone meal to the glow lichen.
• Take note as to whether or not glow lichens can spread into spawn protection.

Observed Behavior:

Glow lichens can spread into spawn protection.

Expected Behavior:

Glow lichens would not be able to spread into spawn protection.