add default implementation to build a group path like Paths.get(...)

src/main/java/org/janelia/saalfeldlab/n5/N5Reader.java

@@ -331,4 +331,29 @@ public default String getGroupSeparator() {
 
 		return "/";
 	}
+
+	/**
+	 * Creates a group path by concatenating all nodes with the node separator
+	 * defined by {@link #getGroupSeparator()}.  The string will not have a
+	 * leading or trailing node separator symbol.
+	 *
+	 * @param nodes
+	 * @return
+	 */
+	public default String groupPath(final String... nodes) {
+
+		if (nodes == null || nodes.length == 0)
+			return "";
+
+		final String groupSeparator = getGroupSeparator();
+		final StringBuilder builder = new StringBuilder(nodes[0]);
+
+		for (int i = 1; i < nodes.length; ++i) {
+
+			builder.append(groupSeparator);
+			builder.append(nodes[i]);
+		}
+
+		return builder.toString();
+	}
 }