code: protected static void appendTo(@Nonnull StringBuilder buf, @Nonnull Map<? extends String, ? extends Object> values) {
          for (Map.Entry<? extends String, ? extends Object> e : values.entrySet()) {
              if (buf.length() > 0)
                  buf.append(",");
              buf.append(e.getKey());
              Object value = e.getValue();
              if (value != null)
                  buf.append('=').append(value);
          }
      }
docs: Allows use of ImmutableMap.of() patterns.