code: @Override
      public Map<String, String> getValues(final String variableContains) {
          final Map<String, String> valueMap = new HashMap<>();
          for (final VariableProvider variableProvider : variableProviderPool) {
              valueMap.putAll(variableProvider.getValues(variableContains));
          }
          return valueMap;
      }
docs: {@inheritDoc}
  
  @param variableContains {@inheritDoc}
  
  @return {@inheritDoc}