#173 solution and added unit test with added test checks

processor/src/main/java/org/mapstruct/ap/processor/MapperCreationProcessor.java

@@ -192,9 +192,11 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Sourc
                     break;
                 }
             }
-
+            Type declaringMapper = mappingMethod.getDeclaringMapper();
             if ( implementationRequired ) {
-                mappingMethods.add( new DelegatingMethod( mappingMethod ) );
+                if ( ( declaringMapper == null ) ||  declaringMapper.equals( typeFactory.getType( element ) ) ) {
+                    mappingMethods.add( new DelegatingMethod( mappingMethod ) );
+                }
             }
         }
 

processor/src/test/java/org/mapstruct/ap/test/decorator/DecoratorTest.java

@@ -113,7 +113,8 @@ public class DecoratorTest extends MapperTestBase {
         //given
         Calendar birthday = Calendar.getInstance();
         birthday.set( 1928, 4, 23 );
-        Person person = new Person( "Gary", "Crant", birthday.getTime(), new Address( "42 Ocean View Drive" ) );
+        Person person = new Person2( "Gary", "Crant", birthday.getTime(), new Address( "42 Ocean View Drive" ) );
+
 
         //when
         PersonDto personDto = YetAnotherPersonMapper.INSTANCE.personToPersonDto( person );
@@ -125,6 +126,43 @@ public class DecoratorTest extends MapperTestBase {
         assertThat( personDto.getAddress().getAddressLine() ).isEqualTo( "42 Ocean View Drive" );
     }
 
+    @IssueKey("173")
+    @Test
+    @WithClasses({
+        Person2Mapper.class,
+        Person2MapperDecorator.class,
+        Person2.class,
+        PersonDto2.class,
+        Employer.class,
+        EmployerDto.class,
+        EmployerMapper.class,
+        SportsClub.class,
+        SportsClubDto.class,
+    })
+    public void shouldApplyCustomMappers() {
+        //given
+        Calendar birthday = Calendar.getInstance();
+        birthday.set( 1928, 4, 23 );
+        Person2 person = new Person2( "Gary", "Crant", birthday.getTime(), new Address( "42 Ocean View Drive" ) );
+        person.setEmployer( new Employer( "ACME" ) );
+        person.setSportsClub( new SportsClub( "SC Duckburg" ) );
+
+        //when
+        PersonDto2 personDto = Person2Mapper.INSTANCE.personToPersonDto( person );
+
+        //then
+        assertThat( personDto ).isNotNull();
+        assertThat( personDto.getName() ).isEqualTo( "Gary Crant" );
+        assertThat( personDto.getAddress() ).isNotNull();
+        assertThat( personDto.getAddress().getAddressLine() ).isEqualTo( "42 Ocean View Drive" );
+        assertThat( personDto.getEmployer() ).isNotNull();
+        assertThat( personDto.getEmployer().getName() ).isNotNull();
+        assertThat( personDto.getEmployer().getName() ).isEqualTo( "ACME" );
+        assertThat( personDto.getSportsClub() ).isNotNull();
+        assertThat( personDto.getSportsClub().getName() ).isNotNull();
+        assertThat( personDto.getSportsClub().getName() ).isEqualTo( "SC Duckburg" );
+    }
+
     @Test
     @WithClasses({
         ErroneousPersonMapper.class,

processor/src/test/java/org/mapstruct/ap/test/decorator/Employer.java

@@ -0,0 +1,42 @@
+/**
+ *  Copyright 2012-2014 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.mapstruct.ap.test.decorator;
+
+/**
+ *
+ * @author Sjaak Derksen
+ */
+public class Employer {
+
+    private String name;
+
+    public Employer() { }
+
+    public Employer( String name ) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/decorator/EmployerDto.java

@@ -0,0 +1,36 @@
+/**
+ *  Copyright 2012-2014 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.mapstruct.ap.test.decorator;
+
+/**
+ *
+ * @author Sjaak Derksen
+ */
+public class EmployerDto {
+
+    private String name;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/decorator/EmployerMapper.java

@@ -0,0 +1,38 @@
+/**
+ *  Copyright 2012-2014 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.mapstruct.ap.test.decorator;
+
+/**
+ *
+ * @author Sjaak Derksen
+ */
+public class EmployerMapper {
+
+    public Employer fromDto(EmployerDto dto) {
+        Employer employer = new Employer();
+        employer.setName( dto.getName() );
+        return employer;
+    }
+
+    public EmployerDto toDto(Employer employer) {
+        EmployerDto dto = new EmployerDto();
+        dto.setName( employer.getName() );
+        return dto;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/decorator/Person2.java

@@ -0,0 +1,52 @@
+/**
+ *  Copyright 2012-2014 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.mapstruct.ap.test.decorator;
+
+import java.util.Date;
+
+/**
+ *
+ * @author Sjaak Derksen
+ */
+public class Person2 extends Person {
+
+    private SportsClub sportsClub;
+
+    private Employer employer;
+
+    public Person2(String firstName, String lastName, Date dateOfBirth, Address address) {
+        super( firstName, lastName, dateOfBirth, address );
+    }
+
+    public SportsClub getSportsClub() {
+        return sportsClub;
+    }
+
+    public void setSportsClub(SportsClub sportsClub) {
+        this.sportsClub = sportsClub;
+    }
+
+    public Employer getEmployer() {
+        return employer;
+    }
+
+    public void setEmployer(Employer employer) {
+        this.employer = employer;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/decorator/Person2Mapper.java

@@ -0,0 +1,47 @@
+/**
+ *  Copyright 2012-2014 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.mapstruct.ap.test.decorator;
+
+import org.mapstruct.DecoratedWith;
+import org.mapstruct.Mapper;
+import org.mapstruct.ReportingPolicy;
+import org.mapstruct.factory.Mappers;
+
+@Mapper(unmappedTargetPolicy = ReportingPolicy.IGNORE, uses = { EmployerMapper.class } )
+@DecoratedWith(Person2MapperDecorator.class)
+public abstract class Person2Mapper {
+
+    public static final Person2Mapper INSTANCE = Mappers.getMapper( Person2Mapper.class );
+
+    public abstract PersonDto2 personToPersonDto(Person2 person);
+
+    public abstract AddressDto addressToAddressDto(Address address);
+
+    public SportsClub fromDto(SportsClubDto dto) {
+        SportsClub sc = new SportsClub();
+        sc.setName( dto.getName() );
+        return sc;
+    }
+
+    public SportsClubDto toDto(SportsClub sc) {
+        SportsClubDto dto = new SportsClubDto();
+        dto.setName( sc.getName() );
+        return dto;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/decorator/Person2MapperDecorator.java

@@ -0,0 +1,37 @@
+/**
+ *  Copyright 2012-2014 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.mapstruct.ap.test.decorator;
+
+public abstract class Person2MapperDecorator extends Person2Mapper {
+
+    private final Person2Mapper delegate;
+
+    public Person2MapperDecorator(Person2Mapper delegate) {
+        this.delegate = delegate;
+    }
+
+    @Override
+    public PersonDto2 personToPersonDto(Person2 person) {
+
+        PersonDto2 dto = delegate.personToPersonDto( person );
+        dto.setName( person.getFirstName() + " " + person.getLastName() );
+
+        return dto;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/decorator/PersonDto2.java

@@ -0,0 +1,46 @@
+/**
+ *  Copyright 2012-2014 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.mapstruct.ap.test.decorator;
+
+/**
+ *
+ * @author Sjaak Derksen
+ */
+public class PersonDto2 extends PersonDto {
+
+    private SportsClubDto sportsClub;
+
+    private EmployerDto employer;
+
+    public SportsClubDto getSportsClub() {
+        return sportsClub;
+    }
+
+    public void setSportsClub(SportsClubDto sportsClub) {
+        this.sportsClub = sportsClub;
+    }
+
+    public EmployerDto getEmployer() {
+        return employer;
+    }
+
+    public void setEmployer(EmployerDto employer) {
+        this.employer = employer;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/decorator/SportsClub.java

@@ -0,0 +1,42 @@
+/**
+ *  Copyright 2012-2014 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.mapstruct.ap.test.decorator;
+
+/**
+ *
+ * @author Sjaak Derksen
+ */
+public class SportsClub {
+
+    private String name;
+
+    public SportsClub() { }
+
+    public SportsClub( String name ) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/decorator/SportsClubDto.java

@@ -0,0 +1,37 @@
+/**
+ *  Copyright 2012-2014 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.mapstruct.ap.test.decorator;
+
+/**
+ *
+ * @author Sjaak Derksen
+ */
+public class SportsClubDto {
+
+    private String name;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+}