rootvector2 opened a new pull request, #618:
URL: https://github.com/apache/commons-csv/pull/618

   `nextToken` evaluates the side-effecting `isDelimiter(c)` twice on the same 
character when `ignoreSurroundingSpaces` is on: once in the leading-whitespace 
skip loop and again in the start-of-token check. `isDelimiter` consumes the 
trailing characters of a multi-character delimiter as it matches, so for a 
delimiter whose first character is whitespace the loop eats the delimiter and 
the second call then peeks past it, mismatches, and the empty field at that 
boundary is dropped. With delimiter `" |"` and `ignoreSurroundingSpaces` 
enabled, `a | |b` parsed to two fields (`a`, `" b"`) instead of three (`a`, 
empty, `b`), and ` |a` to one field (`" a"`) instead of two (empty, `a`). Fixed 
by evaluating `isDelimiter` once in the whitespace loop and reusing that result 
for the start-of-token decision.
   
   Found while auditing the multi-character delimiter look-ahead against 
`ignoreSurroundingSpaces`.
   
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