@Override
    boolean isSmallEnough(long size) {
      if (maxCombine != 0) {
        return size <= maxCombine;
      } else {
        return super.isSmallEnough(size);
      }
    }
Just like Fragment except that the first time allocate is called it returns false indicating
that the allocate failed. In a real system this would only happen if a concurrent allocate
happened. This allows better code coverage.
geode-core/src/test/java/org/apache/geode/internal/offheap/FreeListManagerTest.java