When I tried to develop java with STS for the first time in a long time, I forgot how to install lombok, so make a note.
Ubuntu:16.04.6 64bit SpringToolSuite4:4.5.0.RELEASE lombok:1.18.10
Start the installation with STS closed. lombok download Place the downloaded lombok.jar in the same location as the executable file SpringToolSuite4. Double-click lombok.jar to start it, click Specify location, and specify SpringToolSuite4. Click install / Update to complete.