public String getValue(final String key) {
        Validate.notEmpty(key, "key cannot be empty");
        
        final List<String> allValues = this.getValues(key);
        return allValues != null ? allValues.get(0) : null;
    }
public String getValue(final String key) {
        Validate.notEmpty(key, "key cannot be empty");
        
        final List<String> allValues = this.getValues(key);
        return allValues != null ? allValues.get(0) : null;
    }
public String getValue ( final String key ) { Validate . notEmpty ( key , "key cannot be empty" ) ; final List < String > allValues = this . getValues ( key ) ; return allValues != null ? allValues . get ( 0 ) : null ; }
Returns the first value for the given key
@param key key (case insensitive)
@return single (first) value for the given key or {@code null}, if there is no such a key in this instance
Returns the first value for the given key