@Field
    public void setAttachmentStrategy(String attachmentStrategy) {
        if ("all".equalsIgnoreCase(attachmentStrategy)) {
            setAttachmentStrategy(AttachmentStrategy.ALL);
        } else if ("first_only".equalsIgnoreCase(attachmentStrategy)) {
            setAttachmentStrategy(AttachmentStrategy.FIRST_ONLY);
        } else {
            throw new IllegalArgumentException("attachmentStrategy must be 'all' or 'first_only'");
        }
    }
The implementation of keys should be a LinkedHashMap because
order matters!
<p>
Key is the name of the metadata field, value is the type of column:
boolean, string, int, long

@param keys
tika-pipes/tika-emitters/tika-emitter-jdbc/src/main/java/org/apache/tika/pipes/emitter/jdbc/JDBCEmitter.java