code: @Deprecated
      public void setPageCustomVariable(String key, String value){
          if (value == null){
              removeCustomVariable(PAGE_CUSTOM_VARIABLE, key);
          } else {
              setCustomVariable(PAGE_CUSTOM_VARIABLE, new CustomVariable(key, value), null);
          }
      }
docs: Set a page custom variable with the specified key and value at the first available index.
  All page custom variables with this key will be overwritten or deleted
  @param key the key of the variable to set
  @param value the value of the variable to set at the specified key.  A null value will remove this custom variable
  @deprecated Use the {@link #setPageCustomVariable(CustomVariable, int)} method instead.