I'm trying to use JSR-303 validation and display it's results in jsp page. Here is jsp page code piece which shows error:

<c:set var="Error">
    <form:errors path="name"/>
</c:set>
...
<spring:transform value="${Error}"/>

In the controller I have the following:

@PostMapping(params = "next")
public String next(@Valid @ModelAttribute(COMMAND_NAME) final ProjectNewDetailsCommand cmd,
                   final Errors errors,
                   final Model model,
                   final HttpServletRequest request) {

First, the solution which worked for me is writing a custom Validator class:

@Override
public void validate(Object o, Errors errors) {
    errors.pushNestedPath("project");
    ValidationUtils.rejectIfEmptyOrWhitespace(errors, "name", "error.project.creation.name.required");
    errors.popNestedPath();
}

In this case the appropriate message from messages.properties was applied and show on UI:

error.project.creation.name.required=The name must not be blank.

Here is another case when I use JSR-303 annotation:

public class Project {

    ...
    @Size(max = 100, message = "error.project.creation.size")
    private String name;

In messages.properties there is the message under key error.project.creation.size, I've also tried to add the message with key Size.command.project.name as it's stated in some of the sources. Error object in controller is also not empty and contains validation errors. But when I use this approach with JSR-303 I got the following error:

Caused by: javax.servlet.jsp.JspTagException: No message found under code 'Size' for locale 'en_US'.
    at org.springframework.web.servlet.tags.MessageTag.doEndTag(MessageTag.java:200)

Which means that for some reason Spring tries to apply Size error code instead of error.project.creation.size or Size.command.project.name. Any ideas why this is happening and how to fix this?