title: Why does Spring report a factory method arg as ambiguous?
body: <p>I'm trying to create this bean:</p>
  
  <pre><code>&lt;bean id="myBean" class="java.lang.String" factory-method="valueOf"&gt;
      &lt;constructor-arg name="obj" value="a string" type="java.lang.Object"/&gt;
  &lt;/bean&gt;
  </code></pre>
  
  <p>I want Spring to use this method <code>java.lang.String#valueOf(Object obj)</code> when creating the bean.</p>
  
  <p>I get:</p>
  
  <pre><code>Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'myBean' defined in class path resource [META-INF/test-contexts/testManualDependencyBundleResolverContext.xml]: Unsatisfied dependency expressed through constructor argument with index 0 of type [char[]]: Ambiguous factory method argument types - did you specify the correct bean references as factory method arguments?
  Related cause: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'myBean' defined in class path resource [META-INF/test-contexts/testManualDependencyBundleResolverContext.xml]: Unsatisfied dependency expressed through constructor argument with index 0 of type [char[]]: Ambiguous factory method argument types - did you specify the correct bean references as factory method arguments?
  Related cause: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'myBean' defined in class path resource [META-INF/test-contexts/testManualDependencyBundleResolverContext.xml]: Unsatisfied dependency expressed through constructor argument with index 0 of type [boolean]: Ambiguous factory method argument types - did you specify the correct bean references as factory method arguments?
  Related cause: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'myBean' defined in class path resource [META-INF/test-contexts/testManualDependencyBundleResolverContext.xml]: Unsatisfied dependency expressed through constructor argument with index 0 of type [long]: Ambiguous factory method argument types - did you specify the correct bean references as factory method arguments?
  Related cause: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'myBean' defined in class path resource [META-INF/test-contexts/testManualDependencyBundleResolverContext.xml]: Unsatisfied dependency expressed through constructor argument with index 0 of type [char]: Ambiguous factory method argument types - did you specify the correct bean references as factory method arguments?
  Related cause: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'myBean' defined in class path resource [META-INF/test-contexts/testManualDependencyBundleResolverContext.xml]: Unsatisfied dependency expressed through constructor argument with index 0 of type [double]: Ambiguous factory method argument types - did you specify the correct bean references as factory method arguments?
  Related cause: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'myBean' defined in class path resource [META-INF/test-contexts/testManualDependencyBundleResolverContext.xml]: Unsatisfied dependency expressed through constructor argument with index 0 of type [float]: Ambiguous factory method argument types - did you specify the correct bean references as factory method arguments?
  Related cause: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'myBean' defined in class path resource [META-INF/test-contexts/testManualDependencyBundleResolverContext.xml]: Unsatisfied dependency expressed through constructor argument with index 0 of type [int]: Ambiguous factory method argument types - did you specify the correct bean references as factory method arguments?
  Related cause: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'myBean' defined in class path resource [META-INF/test-contexts/testManualDependencyBundleResolverContext.xml]: Unsatisfied dependency expressed through constructor argument with index 0 of type [java.lang.Object]: Ambiguous factory method argument types - did you specify the correct bean references as factory method arguments?
  </code></pre>
  
  <p>Why? I think I've specified everything needed for Spring to resolve the correct method I want it to use.</p>