rest-assured/src/main/java/io/restassured/config/MultiPartConfig.java
public MultiPartConfig defaultFileName(String defaultFileName) {
        return new MultiPartConfig(defaultControlName, defaultFileName, defaultSubtype, defaultBoundary, defaultCharset, true);
    }
public MultiPartConfig defaultFileName(String defaultFileName) {
        return new MultiPartConfig(defaultControlName, defaultFileName, defaultSubtype, defaultBoundary, defaultCharset, true);
    }
Specify the default filename to use if not defined explicitly in multi-part request.
<p>
Default is {@value #DEFAULT_FILE_NAME}
</p>

@param defaultFileName The file name to use
@return A new instance of {@link MultiPartConfig}