title: Unknown Property in a return type
body: <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>