src/PoFile.php
public static function createKey(?string $msgid, ?string $msgctxt = null, ?string $msgid_plural = null): string
    {
        $key = '';
        if (!empty($msgctxt)) {
            $key .= $msgctxt . '|';
        }
        $key .= (string) $msgid;
        if (!empty($msgid_plural)) {
            $key .= '|' . $msgid_plural;
        }
        return $key;
    }
public static function createKey(?string $msgid, ?string $msgctxt = null, ?string $msgid_plural = null): string
    {
        $key = '';
        if (!empty($msgctxt)) {
            $key .= $msgctxt . '|';
        }
        $key .= (string) $msgid;
        if (!empty($msgid_plural)) {
            $key .= '|' . $msgid_plural;
        }
        return $key;
    }
public static function createKey ( ? string $ msgid , ? string $ msgctxt = null , ? string $ msgid_plural = null ) : string { $ key = '' ; if ( ! empty ( $ msgctxt ) ) { $ key .= $ msgctxt . '|' ; } $ key .= ( string ) $ msgid ; if ( ! empty ( $ msgid_plural ) ) { $ key .= '|' . $ msgid_plural ; } return $ key ; }
Build the internal entries array key from id, context and plural id

@param string|null $msgid        the untranslated message of the entry
@param string|null $msgctxt      the context of the entry, if any
@param string|null $msgid_plural the untranslated plural message of the entry, if any

@return string
Build the internal entries array key from id context and plural id