Jersey 2.x bug. Jersey accepts requests where the content type is not specified (even though the resource is annotated with @consumes(MediaType.APPLICATION_JSON)) and whose body is empty (even though the resource expects non-empty JSON body) -- TheCuriousOne

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>simple-service-2</artifactId>
    <packaging>jar</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>simple-service</name>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.glassfish.jersey</groupId>
                <artifactId>jersey-bom</artifactId>
                <version>${jersey.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.glassfish.jersey.containers</groupId>
            <artifactId>jersey-container-grizzly2-http</artifactId>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.media</groupId>
            <artifactId>jersey-media-json-jackson</artifactId>
            <version>2.2</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.2.2</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.2.2</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>5.0.1.Final</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.9</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.core</groupId>
            <artifactId>jersey-client</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.5.1</version>
                <inherited>true</inherited>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.2.1</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>java</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <mainClass>com.example.Main</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <properties>
        <jersey.version>2.2</jersey.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
</project>

src_main_java_com_example_Main.java

package com.example;

import org.glassfish.grizzly.http.server.HttpServer;
import org.glassfish.jersey.grizzly2.httpserver.GrizzlyHttpServerFactory;
import org.glassfish.jersey.server.ResourceConfig;
import org.glassfish.jersey.jackson.JacksonFeature;

import java.io.IOException;
import java.net.URI;

public class Main
{
    public static final String BASE_URI = "http://localhost:8080";

    public static HttpServer startServer()
    {
        final ResourceConfig rc = new ResourceConfig();

        rc.register(JacksonFeature.class);
        rc.register(new MyResource());

        return GrizzlyHttpServerFactory.createHttpServer(URI.create(BASE_URI), rc);
    }

    public static void main(String[] args) throws IOException
    {
        final HttpServer server = startServer();
        System.out.println(String.format("Jersey app started with WADL available at "
                + "%sapplication.wadl\nHit enter to stop it...", BASE_URI));
        System.in.read();
        server.stop();
    }
}

src_main_java_com_example_MyData.java

package com.example;

import com.fasterxml.jackson.annotation.JsonProperty;
import org.hibernate.validator.constraints.NotEmpty;

public class MyData 
{
    public MyData 
        ( @JsonProperty("a") String a 
        , @JsonProperty("b") String b
        )
    {
        a_m = a;
        b_m = b;
    }

    @JsonProperty("a")
    public String getA()
    {
        return a_m;
    }

    @JsonProperty("b")
    public String getB()
    {
        return b_m;
    }

    @NotEmpty
    private final String b_m;

    @NotEmpty
    private final String a_m;
}

src_main_java_com_example_MyResource.java

package com.example;

import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.QueryParam;
import javax.ws.rs.Produces;
import javax.ws.rs.Consumes;
import javax.ws.rs.core.MediaType;

@Path("/foo")
@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.APPLICATION_JSON)
public class MyResource
{
    @POST
    public String foo(MyData myData)
    {
        System.err.println("MyResource.foo");
        return String.format("myData.a = %s; myData.b = %s\n", myData.getA(), myData.getB());  
    }
}