lib/Configuration.php
public function addDefaultHeader($headerName, $headerValue)
    {
        if (!is_string($headerName)) {
            throw new \InvalidArgumentException('Header name must be a string.');
        }

        $this->defaultHeaders[$headerName] =  $headerValue;
        return $this;
    }
public function addDefaultHeader($headerName, $headerValue)
    {
        if (!is_string($headerName)) {
            throw new \InvalidArgumentException('Header name must be a string.');
        }

        $this->defaultHeaders[$headerName] =  $headerValue;
        return $this;
    }
public function addDefaultHeader ( $ headerName , $ headerValue ) { if ( ! is_string ( $ headerName ) ) { throw new \ InvalidArgumentException ( 'Header name must be a string.' ) ; } $ this -> defaultHeaders [ $ headerName ] = $ headerValue ; return $ this ; }
Adds a default header

@param string $headerName  header name (e.g. Token)
@param string $headerValue header value (e.g. 1z8wp3)

@return ApiClient
Adds a default header