Method is

guava/src/com/google/common/base/CharMatcher.java:297–299

Returns a {@code char} matcher that matches only one specified BMP character.

(char match)

  /** Returns a {@code char} matcher that matches only one specified BMP character. */
  public static CharMatcher is(char match) {
    return new Is(match);
  }

  /**
   * Returns a {@code char} matcher that matches any character except the BMP character specified.