private void updateValue(String testpointId, Short fieldId, Object newValue) {
        if(!testpointFieldValues.containsKey(testpointId)) {
            testpointFieldValues.put(testpointId, new HashMap<>());
        }
        testpointFieldValues.get(testpointId).put(fieldId, newValue);
    }
Updates a single field value for a given testpoint.

@param testpointId id of the testpoint the field belongs to.
@param fieldId id of the field.
@param newValue value the field is set to.
plc4j/protocols/delta-v/src/test/java/org/apache/plc4x/java/deltav/PoCInflux.java