public function testHeaderProcessing()
{
$headers = ["header1" => [], "header2" => ["value"], "header3" => ["value1", "value2"]];
$this->request->shouldReceive("getUri->__toString")->andReturn("");
$this->request->shouldReceive("getBody->getContents")->andReturn("");
$this->request->shouldReceive("getHeaders")->andReturn($headers);
$transferStats = $this->createTransferStats(null, null);
$processor = new ApiRequestProcessor();
$processor->recordTransferStats($transferStats);
$record = ["extra" => []];
$record = $processor($record);
$this->assertArrayHasKey("extra", $record);
$extra = $record["extra"];
$this->assertArrayHasKey("requestHeaders", $extra);
$expected = "header2: value\nheader3: value1\nheader3: value2";
$this->assertEquals($expected, $extra["requestHeaders"]);
}