Ignore empty lines in Graphite plaintext (#3684)

(cherry picked from commit 87830a1c38)

plugins/parsers/graphite/parser.go

@@ -138,8 +138,11 @@ func (p *GraphiteParser) Parse(buf []byte) ([]telegraf.Metric, error) {
 
 		// Trim the buffer, even though there should be no padding
 		line := strings.TrimSpace(string(buf))
-		metric, err := p.ParseLine(line)
+		if line == "" {
+			continue
+		}
 
+		metric, err := p.ParseLine(line)
 		if err == nil {
 			metrics = append(metrics, metric)
 		} else {