code: static int getIndex(CharSequence name, CharSequence value) {
          int index = getIndex(name);
          if (index == -1) {
              return -1;
          }
  
          // Note this assumes all entries for a given header field are sequential.
          while (index <= length) {
              HpackHeaderField entry = getEntry(index);
              if (equalsConstantTime(name, entry.name) == 0) {
                  break;
              }
              if (equalsConstantTime(value, entry.value) != 0) {
                  return index;
              }
              index++;
          }
  
          return -1;
      }
docs: Returns the index value for the given header field in the static table. Returns -1 if the
  header field is not in the static table.