@Override
    public String toString() {
      StringBuilder sb = new StringBuilder();
      boolean first = true;
      for (ResourceInst inst : this) {
        if (first) {
          first = false;
        } else {
          sb.append(" + ");
        }
        sb.append(inst);
      }
      return sb.toString();
    }
Represents a list of ResourceInst that have been combined together. Note the most common case
is for this class to only own a single ResourceInst.
geode-core/src/main/java/org/apache/geode/internal/SystemAdmin.java