guava/src/com/google/common/base/Splitter.java
public Splitter trimResults(CharMatcher trimmer) {
    checkNotNull(trimmer);
    return new Splitter(strategy, omitEmptyStrings, trimmer, limit);
  }
public Splitter trimResults(CharMatcher trimmer) {
    checkNotNull(trimmer);
    return new Splitter(strategy, omitEmptyStrings, trimmer, limit);
  }
TODO(kevinb): throw if a trimmer was already specified!