HeaderExtractor (co.elastic.apm:apm-agent-api 1.7.0 API)

```
public interface HeaderExtractor
```
Used to extract the first header with a specific header name.
Can be implemented as a lambda in Java 8 and as an anonymous inner class in Java 7.

- Method Summary
  
  All Methods Instance Methods Abstract Methods
  Modifier and Type Method Description
  
  String getFirstHeader(String headerName)
  Returns the value of the provided header name

- Method Detail
  - getFirstHeader
```
String getFirstHeader(String headerName)
```
    Returns the value of the provided header name
    
    Parameters:
    
    headerName - the name of the header to extract
    
    Returns:
    
    the value of the provided header name