code: protected boolean getBoolean(String key, boolean defaultValue) {
          try {
              return getConfig().getBoolean(key, defaultValue);
          } catch (ConversionException e) {
              logConversionException(key, e);
          }
          return defaultValue;
      }
docs: Gets the {@code boolean} with the given configuration key.
  <p>
  The default value is returned if the key doesn't exist or it's not a {@code boolean}.
  
  @param key the configuration key.
  @param defaultValue the default value, if the key doesn't exist or it's not a {@code boolean}.
  @return the value of the configuration, or default value.
  @since 2.7.0