Unknown Property in a return type
<p>I am trying to use mapstruct in my Play 2.4 Java8 JPA project. Steps I have done:</p>

<p>Added Dependency</p>

<pre><code>  "org.mapstruct" % "mapstruct-jdk8" % "1.1.0.Beta1",
  "org.mapstruct" % "mapstruct-processor" % "1.1.0.Beta1"
</code></pre>

<p>Model</p>

<pre><code>@Entity
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;            
    private String fullName;          
    private String email;
}
</code></pre>

<p>EmployeeDto</p>

<pre><code>public class EmployeeDto {

    private String full_name;
    private String email;
}
</code></pre>

<p>EmployeeMapper</p>

<pre><code>@Mapper
public interface EmployeeMapper {

    EmployeeMapper INSTANCE = Mappers.getMapper(EmployeeMapper.class);

    @Mapping(source = "fullName", target = "full_name")
    EmployeeDto employeeToEmployeeDto(Employee employee);
}
</code></pre>

<p>But its giving me a compilation error</p>

<pre><code> error: Unknown property "full_name" in return type.
[error]     @Mapping(source = "fullName", target = "full_name")
</code></pre>

<p>What could be the issue for the error?</p>