code: @NonNull
      @SuppressWarnings("unused")
      public ReportBuilder customData(@NonNull Map<String, String> customData) {
          this.customData.putAll(customData);
          return this;
      }
docs: Sets additional values to be added to {@link org.acra.ReportField#CUSTOM_DATA}. Values
  specified here take precedence over globally specified custom data.
  
  @param customData a map of custom key-values to be attached to the report
  @return the updated {@code ReportBuilder}