detectedCharset
Retrieves the charset that was detected by this decoder (optional operation).
If this decoder implements an auto-detecting charset then this method returns the actual charset once it has been detected. After that point, this method returns the same value for the duration of the current decoding operation. If not enough input bytes have yet been read to determine the actual charset then this method throws an [ ].
The default implementation of this method always throws an [ ]; it should be overridden by auto-detecting decoders to return the appropriate value.
Return
The charset detected by this auto-detecting decoder, or null if the charset has not yet been determined
Throws
If insufficient bytes have been read to determine a charset
If this decoder does not implement an auto-detecting charset