Hibernate:el nombre de restricción es nulo en MySQL

Se me ocurrió la siguiente solución:

1. Ampliar Hibernate MySQL5Dialect existente:

   public class MySQL5Dialect extends org.hibernate.dialect.MySQL5Dialect {
   
       /**
       * Pattern to extract violated constraint name from {@link SQLException}.
       */
       private static final Pattern PATTERN = Pattern.compile(".*constraint\\W+(\\w+).*", Pattern.CASE_INSENSITIVE);
   
       private ViolatedConstraintNameExtracter constraintNameExtracter;
   
       public MySQL5Dialect() {
           constraintNameExtracter = new ConstraintNameExtractor();
       }
   
       @Override
       public ViolatedConstraintNameExtracter getViolatedConstraintNameExtracter() {
           return constraintNameExtracter;
       }
   
       private class ConstraintNameExtractor implements ViolatedConstraintNameExtracter {
   
           @Override
           public String extractConstraintName(SQLException sqle) {
               final String msg = sqle.getMessage();
               final Matcher matcher = PATTERN.matcher(msg);
               String constraintName = null;
               if (matcher.matches()) {
                   constraintName = matcher.group(1);
               }
   
               return constraintName;
           }
   
       }
   
   }
   

2. Especifique el dialecto recién creado en el archivo de configuración de Hibernate (hibernate.cfg.xml):

   <property name="dialect">your.package.MySQL5Dialect</property>
   

3. Ahora getConstraintName() devolverá el nombre real de la restricción violada:

   try {
       ...
   } catch (ConstraintViolationException e) {
       LOG.error(String.format("Constraint=%s, code=%d", e.getConstraintName(), e.getErrorCode()));
   }