Fix bean accessors being used for field names

When using `@JsonProperty` on a bean property (i.e. a field with
accessor methods), if you do not specify an explicit name for the
property, the `ScalaAnnotationIntrospector` was incorrectly generating
properties for the accessor methods.

In the following example:

```
class Bean {
  private var value: Int = 0

  @JsonProperty
  def getValue: Int = value

  @JsonProperty
  def setValue(value: Int): Unit = { this.value = value }
}
```

A mapper configured with the `ScalaAnnotationIntrospector` would
serialize this to:

```
{"value":0,"getValue":0}
```

This most notably impacts interop with Java-defined classes, as they
often follow the pattern of Java Beans, where the accessor methods are
annotated with `@JsonProperty`.

Credit for the fix goes to @clintmiller1
(FasterXML#224 (comment)).

I've included a test that verifies the problem, and the solution.

Author: nicktelford

src/main/scala/com/fasterxml/jackson/module/scala/introspect/BeanIntrospector.scala

@@ -194,7 +194,8 @@ object BeanIntrospector {
       if findField(cls, name).isEmpty
       if !name.contains('$')
       if !fields.exists(_.name == name)
-      setter = findSetter(cls, name) if setter.isDefined || getter.getAnnotation(classOf[JsonProperty]) != null
+      getterProperty = getter.getAnnotation(classOf[JsonProperty])
+      setter = findSetter(cls, name) if setter.isDefined || (getterProperty != null && getterProperty.value != JsonProperty.USE_DEFAULT_NAME)
       beanGetter = findBeanGetter(cls, name)
       beanSetter = findBeanSetter(cls, name)
     } yield PropertyDescriptor(name, None, None, Some(getter), setter, beanGetter, beanSetter)

src/test/scala/com/fasterxml/jackson/module/scala/introspect/ScalaAnnotationIntrospectorTest.scala

@@ -2,6 +2,7 @@ package com.fasterxml.jackson
 package module.scala
 package introspect
 
+import com.fasterxml.jackson.annotation.JsonProperty
 import com.fasterxml.jackson.core.JsonGenerator
 import com.fasterxml.jackson.databind
 import com.fasterxml.jackson.databind.module.SimpleModule
@@ -24,6 +25,11 @@ object ScalaAnnotationIntrospectorTest
   class BeanPropertyClass(@BeanProperty val param: Int)
   class AnnotatedBasicPropertyClass(@JsonScalaTestAnnotation val param: Token)
   class AnnotatedBeanPropertyClass(@JsonScalaTestAnnotation @BeanProperty val param: Token)
+  class JavaBeanPropertyClass {
+    private var value: Int = 0
+    @JsonProperty def getValue: Int = value
+    @JsonProperty def setValue(value: Int): Unit = { this.value = value }
+  }
 }
 
 @RunWith(classOf[JUnitRunner])
@@ -118,6 +124,13 @@ class ScalaAnnotationIntrospectorTest extends fixture.FlatSpec with Matchers {
     mapper.writeValueAsString(bean)
   }
 
+  it should "correctly infer name(s) of un-named bean properties" in { mapper =>
+    val tree = mapper.valueToTree[databind.node.ObjectNode](new JavaBeanPropertyClass)
+    tree.has("value") shouldBe true
+    tree.has("setValue") shouldBe false
+    tree.has("getValue") shouldBe false
+  }
+
   private def getProps(mapper: ObjectMapper, bean: AnyRef) = {
     val config = mapper.getSerializationConfig
     val beanDescription: BeanDescription = config.introspect(mapper.constructType(bean.getClass))