private static void addMetadata(Metadata metadata, Property property, List<String> values) {
        if (values != null) {
            for (String value : values) {
                addMetadata(metadata, property, value);
            }
        }
    }
Add list to the metadata map.

@param metadata the metadata map to update.
@param property the property to add.
@param values the values to add.
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-xmp-commons/src/main/java/org/apache/tika/parser/xmp/XMPMetadataExtractor.java