Merge findInjectableValues() results in AnnotationIntrospectorPair

As many AnnotationIntrospector implementations use default values
for useInput, allow the secondary introspector's useInput value to
combine with the primary's id to prevent losing the useInput value.

Fixes a special case of #962 seen by the GuiceAnnotationInspector
in FasterXML/jackson-modules-base#134

src/main/java/com/fasterxml/jackson/databind/introspect/AnnotationIntrospectorPair.java

@@ -300,7 +300,11 @@ public NameTransformer findUnwrappingNameTransformer(AnnotatedMember member) {
     @Override
     public JacksonInject.Value findInjectableValue(AnnotatedMember m) {
         JacksonInject.Value r = _primary.findInjectableValue(m);
-        return (r == null) ? _secondary.findInjectableValue(m) : r;
+        if (r == null || r.getUseInput() == null) {
+            JacksonInject.Value secondary = _secondary.findInjectableValue(m);
+            r = (r == null || secondary == null) ? secondary : r.withUseInput(secondary.getUseInput());
+        }
+        return r;
     }
 
     @Override

src/test/java/com/fasterxml/jackson/databind/introspect/AnnotationIntrospectorPairTest.java

@@ -0,0 +1,103 @@
+package com.fasterxml.jackson.databind.introspect;
+
+import com.fasterxml.jackson.annotation.JacksonInject;
+import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.OptBoolean;
+import com.fasterxml.jackson.databind.AnnotationIntrospector;
+import com.fasterxml.jackson.databind.BeanProperty;
+import com.fasterxml.jackson.databind.DeserializationContext;
+import com.fasterxml.jackson.databind.InjectableValues;
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.json.JsonMapper;
+import junit.framework.TestCase;
+
+public class AnnotationIntrospectorPairTest extends TestCase {
+
+    static class TestIntrospector extends NopAnnotationIntrospector {
+        @Override
+        public JacksonInject.Value findInjectableValue(AnnotatedMember m) {
+            if (m.getRawType() == UnreadableBean.class) {
+                return JacksonInject.Value.forId("jjj");
+            }
+            return null;
+        }
+    }
+
+    static class TestInjector extends InjectableValues {
+
+        @Override
+        public Object findInjectableValue(Object valueId, DeserializationContext ctxt, BeanProperty forProperty, Object beanInstance) {
+            if (valueId == "jjj") {
+                UnreadableBean bean = new UnreadableBean();
+                bean.setValue(1);
+                return bean;
+            }
+            return null;
+        }
+    }
+
+    enum SimpleEnum { ONE, TWO }
+
+    static class UnreadableBean {
+        public SimpleEnum value;
+
+        public void setValue(SimpleEnum value) {
+            this.value = value;
+        }
+
+        public void setValue(Integer intValue) {
+            this.value = SimpleEnum.values()[intValue];
+        }
+
+        public SimpleEnum getValue() {
+            return value;
+        }
+    }
+
+    static class ReadableInjectedBean {
+        public ReadableInjectedBean(@JacksonInject(useInput = OptBoolean.FALSE) UnreadableBean injectBean) {
+            this.injectBean = injectBean;
+        }
+        @JsonProperty
+        private String foo;
+        @JsonIgnore
+        private UnreadableBean injectBean;
+    }
+
+    static class UnreadableInjectedBean {
+        public UnreadableInjectedBean(@JacksonInject UnreadableBean injectBean) {
+            this.injectBean = injectBean;
+        }
+        @JsonProperty
+        private String foo;
+        @JsonIgnore
+        private UnreadableBean injectBean;
+    }
+
+    public void testMergingIntrospectors() throws Exception {
+        AnnotationIntrospector testInstrospector = new TestIntrospector();
+        ObjectMapper mapper = new JsonMapper();
+        mapper.setInjectableValues(new TestInjector());
+        mapper.setAnnotationIntrospectors(
+                new AnnotationIntrospectorPair(testInstrospector,
+                                               mapper.getSerializationConfig().getAnnotationIntrospector()),
+                new AnnotationIntrospectorPair(testInstrospector,
+                                               mapper.getDeserializationConfig().getAnnotationIntrospector())
+        );
+        ReadableInjectedBean bean = mapper.readValue("{\"foo\": \"bob\"}", ReadableInjectedBean.class);
+        assertEquals("bob", bean.foo);
+        assertEquals(SimpleEnum.TWO, bean.injectBean.value);
+
+        boolean successReadingUnreadableInjectedBean;
+        try {
+            UnreadableInjectedBean noBean = mapper.readValue("{\"foo\": \"bob\"}", UnreadableInjectedBean.class);
+            successReadingUnreadableInjectedBean = true;
+        } catch (JsonMappingException e) {
+            successReadingUnreadableInjectedBean = false;
+            assertTrue(e.getMessage().contains("Conflicting setter definitions"));
+        }
+        assertFalse(successReadingUnreadableInjectedBean);
+    }
+}