PlantUML Relationship Reverser is a tool for reversing relationships in several diagrams on PlantUML, including class diagrams, ERDs (Entity-Relationship Diagrams) and the other diagrams.
Features

Reverse the relationship between the classes as follows.
"Class A" "*" *-[#blue,thickness=2]-> "1..5" "Class B" : > label
⇔
"Class B" "1..5" <-[#blue,thickness=2]-* "*" "Class A" : < label
Just place the cursor on the line you want to change and press Ctrl+Shift+/.
Pressing Ctrl+Shift+Alt+/ swaps the only classes or entities while keeping the relationship or arrow intact.
"Class A" "1" -up-> "1..5" "Class B" : > label
⇔
"Class B" "1..5" -up-> "1" "Class A" : > label
It supports not only class diagrams but also other types of diagrams, such as ERDs (Entity-Relationship Diagrams). It also supports all types of relationships and arrows supported by PlantUML.
Release Notes
Users appreciate release notes as you update your extension.
1.0.0
Initial release.