rest-assured/src/main/java/io/restassured/authentication/FormAuthConfig.java
public FormAuthConfig withAdditionalFields(String firstFieldName, String secondFieldName, String... additionalFieldNames) {
        notNull(firstFieldName, "First additional field name");
        notNull(secondFieldName, "Second additional field name");
        List<String> list = new ArrayList<String>(additionalInputFieldNames);
        list.add(firstFieldName);
        list.add(secondFieldName);
        if (additionalFieldNames != null && additionalFieldNames.length > 0) {
            list.addAll(Arrays.asList(additionalFieldNames));
        }
        return new FormAuthConfig(formAction, userInputTagName, passwordInputTagName, logDetail, logConfig, csrfFieldName, autoDetectCsrfFieldName, sendCsrfTokenAsFormParam, list);
    }
public FormAuthConfig withAdditionalFields(String firstFieldName, String secondFieldName, String... additionalFieldNames) {
        notNull(firstFieldName, "First additional field name");
        notNull(secondFieldName, "Second additional field name");
        List<String> list = new ArrayList<String>(additionalInputFieldNames);
        list.add(firstFieldName);
        list.add(secondFieldName);
        if (additionalFieldNames != null && additionalFieldNames.length > 0) {
            list.addAll(Arrays.asList(additionalFieldNames));
        }
        return new FormAuthConfig(formAction, userInputTagName, passwordInputTagName, logDetail, logConfig, csrfFieldName, autoDetectCsrfFieldName, sendCsrfTokenAsFormParam, list);
    }
Include multiple additional fields when using form authentication by including input field values with the specified name.
This is the same as {@link #withAdditionalField(String)} but for multiple fields.

<p/>
<b>Important:</b> When including an additional field without specifying a value then REST Assured <b>must always</b> make an additional request to the server in order to
be able to figure out the field value. This will slow down the tests.

@param firstFieldName The first additional input field to include
@param secondFieldName The second additional input field to include
@param additionalFieldNames Additional field name to include (optional)
@return A new FormAuthConfig instance.