code: public void addDataUsageFor(String activity, String attribute) throws CompatibilityException {
                  setDataUsageFor(activity, attribute, new HashSet<>(validUsageModes));
          }
docs: Adds a data attribute for an activity.<br>
  The given activity/attributes have to be known by the context, i.e.
  be contained in the activity/attribute list.
  
  @param activity Activity for which the attribute usage is set.
  @param attribute Attribute used by the given activity.
  @throws ParameterException
  @throws CompatibilityException
  @throws IllegalArgumentException If the given activity/attributes are
  not known.
  @see #getActivities()
  @see #getAttributes()
  @see #setAttributes(Set)