Set MissingMandatoryValueException constructor private

src/main/java/com/ippon/pouet/common/domain/error/MissingMandatoryValueException.java

@@ -2,7 +2,7 @@ package com.ippon.pouet.common.domain.error;
 
 public class MissingMandatoryValueException extends PouetException {
 
-  protected MissingMandatoryValueException(PouetExceptionBuilder builder) {
+  private MissingMandatoryValueException(PouetExceptionBuilder builder) {
     super(builder);
   }