code: protected KeyBucket getBucket(char c) {
          if (c > this.buckets.length) {
              // can't handle non-ASCII chars
              return null;
          }
          int index = c;
          // if we're case-insensitive, push uppercase into lowercase buckets
          if (!isCaseSensitive() && (c >= 'A' && c <= 'Z')) {
              index += 32;
          }
          return this.buckets[index];
      }
docs: Access the bucket for this specific character.
  
  @param c
  @return HeaderBucket