Multimap serializer ignores _valueTypeSerializer

src/main/java/com/fasterxml/jackson/datatype/guava/ser/MultimapSerializer.java

@@ -316,7 +316,11 @@ private final void serializeFields(Multimap<?, ?> mmap, JsonGenerator gen, Seria
                         serializers = _dynamicValueSerializers;
                     }
                 }
-                valueSer.serialize(vv, gen, provider);
+                if (_valueTypeSerializer == null) {
+                    valueSer.serialize(vv, gen, provider);
+                } else {
+                    valueSer.serializeWithType(vv, gen, provider, _valueTypeSerializer);
+                }
             }
             gen.writeEndArray();
         }

src/test/java/com/fasterxml/jackson/datatype/guava/TestMultimaps.java

@@ -3,6 +3,9 @@
 import com.fasterxml.jackson.annotation.*;
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.datatype.guava.pojo.AddOp;
+import com.fasterxml.jackson.datatype.guava.pojo.MathOp;
+import com.fasterxml.jackson.datatype.guava.pojo.MulOp;
 
 import com.google.common.collect.*;
 
@@ -11,6 +14,7 @@
 import java.util.Map;
 
 import static com.google.common.collect.TreeMultimap.create;
+import static junit.framework.TestCase.assertEquals;
 
 /**
  * Unit tests to verify handling of various {@link Multimap}s.
@@ -254,4 +258,53 @@ public void testIssue67() throws IOException
         assertEquals(Maps.immutableEntry("a", 7), iterator.next());
         assertEquals(Maps.immutableEntry("a", 8), iterator.next());
     }
+
+    public void testPolymorphicValue() throws IOException {
+        ImmutableMultimapWrapper input = new ImmutableMultimapWrapper(ImmutableMultimap.of("add", new AddOp(3, 2), "mul", new MulOp(4, 6)));
+
+        String json = MAPPER.writeValueAsString(input);
+
+        ImmutableMultimapWrapper output = MAPPER.readValue(json, ImmutableMultimapWrapper.class);
+        assertEquals(input, output);        
+    }
+
+    public static class ImmutableMultimapWrapper {
+
+        private ImmutableMultimap<String, MathOp> multimap;
+
+        public ImmutableMultimapWrapper() {
+        }
+
+        public ImmutableMultimapWrapper(ImmutableMultimap<String, MathOp> f) {
+            this.multimap = f;
+        }
+
+        public ImmutableMultimap<String, MathOp> getMultimap() {
+            return multimap;
+        }
+
+        public void setMultimap(ImmutableMultimap<String, MathOp> multimap) {
+            this.multimap = multimap;
+        }
+
+        @Override
+        public int hashCode() {
+            int hash = 7;
+            hash = 97 * hash + (this.multimap != null ? this.multimap.hashCode() : 0);
+            return hash;
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (obj == null) {
+                return false;
+            }
+            if (getClass() != obj.getClass()) {
+                return false;
+            }
+            final ImmutableMultimapWrapper other = (ImmutableMultimapWrapper) obj;
+            return !(this.multimap != other.multimap && (this.multimap == null || !this.multimap.equals(other.multimap)));
+        }
+
+    }
 }

src/test/java/com/fasterxml/jackson/datatype/guava/pojo/AddOp.java

@@ -0,0 +1,58 @@
+package com.fasterxml.jackson.datatype.guava.pojo;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+/**
+ *
+ * @author Marcin Kamionowski
+ */
+public class AddOp implements MathOp {
+
+    private final int left;
+    private final int right;
+
+    @JsonCreator
+    public AddOp(
+            @JsonProperty("left") int left,
+            @JsonProperty("right") int right) {
+        this.left = left;
+        this.right = right;
+    }
+
+    public int getLeft() {
+        return left;
+    }
+
+    public int getRight() {
+        return right;
+    }
+
+    public int value() {
+        return left + right;
+    }
+
+    @Override
+    public int hashCode() {
+        int hash = 3;
+        hash = 47 * hash + this.left;
+        hash = 47 * hash + this.right;
+        return hash;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        final AddOp other = (AddOp) obj;
+        if (this.left != other.left) {
+            return false;
+        }
+        return this.right == other.right;
+    }
+
+}

src/test/java/com/fasterxml/jackson/datatype/guava/pojo/MathOp.java

@@ -0,0 +1,17 @@
+package com.fasterxml.jackson.datatype.guava.pojo;
+
+import com.fasterxml.jackson.annotation.JsonSubTypes;
+import com.fasterxml.jackson.annotation.JsonSubTypes.Type;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+
+/**
+ *
+ * @author Marcin Kamionowski
+ */
+@JsonTypeInfo(use=JsonTypeInfo.Id.NAME, include=JsonTypeInfo.As.PROPERTY, property="_t")
+@JsonSubTypes({
+    @Type(name="add", value=AddOp.class), 
+    @Type(name="mul", value=MulOp.class)})
+public interface MathOp {
+
+}

src/test/java/com/fasterxml/jackson/datatype/guava/pojo/MulOp.java

@@ -0,0 +1,58 @@
+package com.fasterxml.jackson.datatype.guava.pojo;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+/**
+ *
+ * @author Marcin Kamionowski
+ */
+public class MulOp implements MathOp {
+
+    private final int left;
+    private final int right;
+
+    @JsonCreator
+    public MulOp(
+            @JsonProperty("left") int left,
+            @JsonProperty("right") int right) {
+        this.left = left;
+        this.right = right;
+    }
+
+    public int getLeft() {
+        return left;
+    }
+
+    public int getRight() {
+        return right;
+    }
+
+    public int value() {
+        return left * right;
+    }
+
+    @Override
+    public int hashCode() {
+        int hash = 7;
+        hash = 67 * hash + this.left;
+        hash = 67 * hash + this.right;
+        return hash;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        final MulOp other = (MulOp) obj;
+        if (this.left != other.left) {
+            return false;
+        }
+        return this.right == other.right;
+    }
+
+}