We have RemoveBracesFormatter, which removes the outer braces. See org.jabref.logic.formatter.bibtexfields.RemoveBracesFormatterTest for examples.

We have org.jabref.model.entry.Author#removeStartAndEndBraces, which also removes inner braces enclosing complete words:

• {Vall{\'e}e} {Poussin} -> Vall{\'e}e Poussin <-- here, {Poussin} is changed to Poussin. This is not available to users (in the cleanup entry dialogue)
• {Vall{\'e}e Poussin} -> Vall{\'e}e Poussin <-- here, the outer braces are removed
• Vall{\'e}e Poussin -> Vall{\'e}e Poussin <-- here, everything is kept as is

We should make this formatter "globally" available:

1. Rename RemoveBracesFormatter to RemoveEnclosingBracesFormatter.
   • Also rename all used fields.
2. Introduce RemoveWordEnclosingAndOuterEnclosingBracesFormatter by moving the code of org.jabref.model.entry.Author#removeStartAndEndBraces to here
   • Introduce class
   • Create test cases (similar to RemoveBracesFormatterTest)
   • Replace call to removeStartAndEndBraces in Author to call to RemoveWordEnclosingAndOuterEnclosingBracesFormatter.format. The RemoveWordEnclosingAndOuterEnclosingBracesFormatter needs to be initialized as class constant in Author
   • Name the formatter "Remove word enclosing braces"
   • Use description "Removes braces encapsulating a complete word and the complete field content."
3. Create a pull request for the user documentation (update the page https://docs.jabref.org/finding-sorting-and-cleaning-entries/saveactions#remove-enclosing-braces).