/usr/share/mate/autostart/caja-dropbox-autostart.desktop is in ubuntu-mate-default-settings 18.04.17.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 | [Desktop Entry]
Name=Create an autostart for Caja Dropbox
Comment=Creates an autostart for Caja Dropbox if it is installed and an autostart is not missing.
Exec=caja-dropbox-autostart
Terminal=false
Type=Application
Icon=caja-dropbox
Categories=Network;FileTransfer;
StartupNotify=false
OnlyShowIn=MATE;
NoDisplay=true
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