question: static protected void assertField ( final String header , final String [ ] fields , final int field , final String expected ) { if ( header == null ) throw new IllegalArgumentException ( ) ; if ( fields == null ) throw new IllegalArgumentException ( ) ; if ( expected == null ) throw new IllegalArgumentException ( ) ; if ( field < 0 ) throw new IllegalArgumentException ( ) ; if ( field >= fields . length ) throw new AssertionFailedError ( "There are only " + fields . length + " fields, but field=" + field + "\n" + header ) ; if ( ! expected . equals ( fields [ field ] ) ) { throw new AssertionFailedError ( "Expected field=" + field + " to be [" + expected + "], actual=" + fields [ field ] + "\n" + header ) ; } }
target:  Used to verify that the header corresponds to our expectations. Logs errors when the expectations are not met.