git clone https://github.com/MosHelper/spring-boot-validation-example.git

compile('org.springframework.boot:spring-boot-starter-validation')

@NotNull
int id;
@Size(min=2)
String name;
@Email(message = "Email not valid.")
String email;

@PostMapping("/post")
public Student postStudent(@Valid @RequestBody Student student){
    return student;
}

{
	"id":2,
	"name":"s",
	"email":"testtest" // <--- not email valid
}

{
    "timestamp": "2018-06-19T07:56:51.406+0000",
    "status": 400,
    "error": "Bad Request",
    "errors": [
        {
            "codes": [
                "Email.student.email",
                "Email.email",
                "Email.java.lang.String",
                "Email"
            ],
            "arguments": [
                {
                    "codes": [
                        "student.email",
                        "email"
                    ],
                    "arguments": null,
                    "defaultMessage": "email",
                    "code": "email"
                },
                [],
                {
                    "defaultMessage": ".*",
                    "arguments": null,
                    "codes": [
                        ".*"
                    ]
                }
            ],
            "defaultMessage": "Email not valid.",
            "objectName": "student",
            "field": "email",
            "rejectedValue": "testtest",
            "bindingFailure": false,
            "code": "Email"
        }
    ],
    "message": "Validation failed for object='student'. Error count: 1",
    "path": "/post"
}