@Nullable
    private String getCredentials(String header) {
        if (header == null) {
            return null;
        }

        final int space = header.indexOf(' ');
        if (space <= 0) {
            return null;
        }

        final String method = header.substring(0, space);
        if (!prefix.equalsIgnoreCase(method)) {
            return null;
        }

        return header.substring(space + 1);
    }
@ Nullable private String getCredentials ( String header ) { if ( header == null ) { return null ; } final int space = header . indexOf ( ' ' ) ; if ( space <= 0 ) { return null ; } final String method = header . substring ( 0 , space ) ; if ( ! prefix . equalsIgnoreCase ( method ) ) { return null ; } return header . substring ( space + 1 ) ; }
Parses a value of the `Authorization` header in the form of `Bearer a892bf3e284da9bb40648ab10`.

@param header the value of the `Authorization` header
@return a token