code: private String getPropertyFromEnvironment(Key key) {
          final String envVariable = key.getPropertyName().toUpperCase().replace(".", "_");
          try {
              return StringUtils.trimToNull(System.getenv(envVariable));
          } catch (SecurityException e) {
              LOGGER.warn("A security exception prevented access to the environment variable. Using defaults.");
          } catch (NullPointerException e) {
              // Do nothing. The key was not specified in an environment variable. Continue along.
          }
          return null;
      }
docs: Attempts to retrieve the key via environment variable. Property names are
  always upper case with periods replaced with underscores.
  
  alpine.worker.threads
  becomes
  ALPINE_WORKER_THREADS
  
  @param key the key to retrieve from environment
  @return the value of the key (if set), null otherwise.
  @since 1.4.3