code: static EncodingInfo getEncodingInfo(String encoding)
      {
          EncodingInfo ei;
  
          String normalizedEncoding = toUpperCaseFast(encoding);
          ei = (EncodingInfo) _encodingTableKeyJava.get(normalizedEncoding);
          if (ei == null)
              ei = (EncodingInfo) _encodingTableKeyMime.get(normalizedEncoding);
          if (ei == null) {
              // We shouldn't have to do this, but just in case.
              ei = new EncodingInfo(null,null, '\u0000');
          }
  
          return ei;
      }
docs: Returns the EncodingInfo object for the specified
  encoding, never null, although the encoding name
  inside the returned EncodingInfo object will be if
  we can't find a "real" EncodingInfo for the encoding.
  <p>
  This is not a public API.
  
  @param encoding The encoding
  @return The object that is used to determine if
  characters are in the given encoding.
  @xsl.usage internal