title: Show list of possible valid xml element values
body: <p>I have following Xml schema.</p>
  
  
  
  <pre><code>&lt;xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema"&gt;
    &lt;xs:simpleType name="type"&gt;
      &lt;xs:restriction base="xs:string"&gt;
        &lt;xs:enumeration value="Type 1" /&gt;
        &lt;xs:enumeration value="Type 2" /&gt;
        &lt;xs:enumeration value="Type 3" /&gt;
      &lt;/xs:restriction&gt;
    &lt;/xs:simpleType&gt;
    &lt;xs:element name="Root"&gt;
      &lt;xs:complexType&gt;
        &lt;xs:sequence&gt;
          &lt;xs:element name="Element_1"&gt;
            &lt;xs:complexType&gt;
              &lt;xs:sequence&gt;
                &lt;xs:element name="TypeName" type="type" /&gt;
              &lt;/xs:sequence&gt;
            &lt;/xs:complexType&gt;
          &lt;/xs:element&gt;
          &lt;xs:element name="Element_2"&gt;
            &lt;xs:complexType&gt;
              &lt;xs:sequence&gt;
                &lt;xs:element name="TypeName" type="type" /&gt;
              &lt;/xs:sequence&gt;
            &lt;/xs:complexType&gt;
          &lt;/xs:element&gt;
        &lt;/xs:sequence&gt;
      &lt;/xs:complexType&gt;
    &lt;/xs:element&gt;
  &lt;/xs:schema&gt;
  </code></pre>
  
  <p>I am validating following xml against the above schema.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;Root&gt;
      &lt;Element_1&gt;
          &lt;TypeName&gt;Type 4&lt;/TypeName&gt;
      &lt;/Element_1&gt;
      &lt;Element_3&gt;
          &lt;TypeName&gt;Type 2&lt;/TypeName&gt;
      &lt;/Element_3&gt;
  &lt;/Root&gt;
  </code></pre>
  
  <p>I am expecting a validation error and I get one:
  <em>The 'TypeName' element is invalid - The value 'Type 4' is invalid according to its datatype 'type' - The Enumeration constraint failed.
  The element 'Root' has invalid child element 'Element_3'. List of possible elements expected: 'Element_2'.</em></p>
  
  <p>The Error message clearly shows the invalid elements (Element_3) and also displays list of possible valid elements (Element_2). Is it possible to display the valid list of 'TypeName'. </p>
  
  <p>Now, I want error message similar to the one below:
  <em>The 'TypeName' element is invalid - The value 'Type 4' is invalid according to its datatype 'type'. <strong>List of possible values expected: 'Type 1, Type 2'</strong> - The Enumeration constraint failed.
  The element 'Root' has invalid child element 'Element_3'. List of possible elements expected: 'Element_2'.</em></p>
  
  <p>Is it possible to get above error message (or similar). Does any other restrictions other than xs:enumeration show all the valid values?</p>