code: @SuppressWarnings({"unused", "WeakerAccess"})
      public void removeMultiValueForKey(String key, String value) {
  
          //noinspection ConstantConditions
          if (value == null || value.isEmpty()) {
              _generateEmptyMultiValueError(key);
              return;
          }
  
          removeMultiValuesForKey(key, new ArrayList<>(Collections.singletonList(value)));
      }
docs: Remove a unique value from a multi-value user profile property
  <p/>
  If the key currently contains a scalar value, prior to performing the remove operation
  the key will be promoted to a multi-value property with the current value cast to a string.
  If the multi-value property is empty after the remove operation, the key will be removed.
  
  @param key   String
  @param value String