code: public int getOrdinal() {
          String configOrdinal = getValue(CONFIG_ORDINAL);
          if (configOrdinal != null) {
              try {
                  return Integer.parseInt(configOrdinal);
              } catch (NumberFormatException ignored) {
                  // Ignored
              }
          }
          return DEFAULT_ORDINAL;
      }
docs: Return the ordinal for this config source. If a property is specified in multiple config sources, the value
  in the config source with the highest ordinal takes precedence.
  For the config sources with the same ordinal value, the config source names will
  be used for sorting according to string sorting criteria.
  Note that this property only gets evaluated during ConfigSource discovery.
  <p>
  The default ordinals for the default config sources:
  <ol>
  <li>System properties (default ordinal=400)</li>
  <li>Environment properties (default ordinal=300)</li>
  <li>/META-INF/microprofile-config.properties (default ordinal=100)</li>
  </ol>
  <p>
  <p>
  Any ConfigSource part of an application will typically use an ordinal between 0 and 200.
  ConfigSource provided by the container or 'environment' typically use an ordinal higher than 200.
  A framework which intends have values overwritten by the application will use ordinals between 0 and 100.
  The property "config_ordinal" can be specified to override the default value.
  
  @return the ordinal value