remove static from private method

Author: David Baum

generator2/org.getaviz.generator/src/main/java/org/getaviz/generator/rd/m2m/RD2RD.java

@@ -374,7 +374,7 @@ private Iterator<Node> getRootDisks() {
 				.stream().map(s -> s.get("d").asNode()).collect(Collectors.toList()).listIterator();
 	}
 
-	private static String removeBrackets(List<String> list) {
+	private String removeBrackets(List<String> list) {
 		return StringUtils.remove(StringUtils.remove(list.toString(), "["), "]");
 	}
 }