code: public int ensureCapacity(int requiredCapacity, int currentCapacity) {
          if (requiredCapacity > currentCapacity) {
              int newCapacity = (currentCapacity * 3) / 2 + 1;
              if (newCapacity < requiredCapacity) {
                  newCapacity = requiredCapacity;
              }
              return newCapacity;
          } else {
              return currentCapacity;
          }
      }
docs: /* (non-Javadoc)
  @see org.jsmpp.util.CapacityPolicy#ensureCapacity(int, int)