@Field
    public void setKeys(Map<String, String> keys) {
        this.keys = keys;
    }
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