code: @XmlElement(name = "totalPages", required = true)
      @JsonProperty(value = "totalPages", required = true)
      @ApiModelProperty(value = "The total size of available pages.", position = 3, required = true, readOnly = true)
      @Override
      public int getTotalPages() {
          if (getTotalSize() <= 0L) {
              return 1;
          }
          return (int) Math.ceil((double) getTotalSize() / (double) getPageRequest().getPageSize());
      }
docs: Returns the number of all pages.
  
  @return the number of all pages