code: public static int getInt(String key, int def) {
          String value = get(key);
          if (value == null) {
              return def;
          }
  
          value = value.trim();
          try {
              return Integer.parseInt(value);
          } catch (Exception e) {
              // Ignore
          }
  
          logger.warn(
                  "Unable to parse the integer system property '{}':{} - using the default value: {}",
                  key, value, def
          );
  
          return def;
      }
docs: Returns the value of the Java system property with the specified
  {@code key}, while falling back to the specified default value if
  the property access fails.
  
  @return the property value.
  {@code def} if there's no such property or if an access to the
  specified property is not allowed.