private void setPropertyValue(ProjectId projectId, String propertyName, String propertyValue) {
try {
WRITE_LOCK.lock();
ProjectInstance pi = getProjectInstance(projectId);
MetaProject mp = getMetaProject();
PropertyValue pv = mp.createPropertyValue(propertyName, propertyValue);
Set<PropertyValue> propertyValues = new HashSet<PropertyValue>(pi.getPropertyValues());
for(Iterator<PropertyValue> it = propertyValues.iterator(); it.hasNext(); ) {
PropertyValue curPv = it.next();
if(curPv.getPropertyName().equals(propertyName)) {
it.remove();