• [java,apex] Remove deprecated and unused rules #2022
• [all] Use slf4j #896
  • done by [all] Use slf4j and SimpleLogger #3789
• [ant] Split off Ant integration into a new submodule #4080
  • (was: Move PMDTask into separate module, to get rid of general ant dependency)
• [cli] Split off CLI implementation into a pmd-cli submodule #4079
• [javascript] Update Rhino library to 1.7.13 #699 (done for PMD 6 by [javascript] Update Rhino library to 1.7.13 #3242)
• [apex] Apex should only have a single RootNode #1937

Remaining tasks

Probably for PMD 7

• [all] Use JUnit5 #3797
• [core] Remove unnecessary property color and system property pmd.color in TextColorRenderer #4312

Postponed

• Minor license switch: From "BSD-style" to standard BSD-3-Clause #4310
• [plsql] Document DBURI data source possibility #4216
• [apex] AST cleanups #4311
• [plsql] Rework grammar for better maintainability #1500