Bug 91823

Schema Based code completion should provide completion values for attributes of
type enumeration.

If a user is authoring an xml file with the schema support, and asks for
completion for the value of attribute of type enumeration, Schema Based
completion must provide list of valid values with respect to attribute's type.

For example consider the following xml file which needs completion for attribute
'modifier':

<component xmlns='http://www.sun.com/schema/SPS'
  xsi:schemaLocation='http://www.sun.com/schema/SPS ../schema/component.xsd' 
  modifier="[CTRL_SPACE]">

    <extends>
        <type name='system#file'></type>
    </extends>
</component>

--------------SCHEMA-----------------
...
  <simpleType name="modifierEnumType">
    <restriction base="string">
      <enumeration value="ABSTRACT"/>
      <enumeration value="FINAL"/>
    </restriction>
  </simpleType>
...
------------SCHEMA-END---------------

If user ask for completion for the 'modifier' attribute, where 'modifier'
attribute is of type 'modifierEnumType', schema based code-completion should
read the schema and provide the valid values that is 'ABSTRACT' & 'FINAL' in our
example.

Currently schema based code completion is not providing the values for
Enumeration type attributes but validation against schema will detect the error
if user provide some invalid value. Following is the error I got when I provide
the value 'abc' instead of values 'ABSTRACT' or 'FINAL'.

----------------------------------OUTPUT------------------------------------
Value 'abc' is not facet-valid with respect to enumeration '[ABSTRACT, FINAL]'.
It must be a value from the enumeration.

The value 'abc' of attribute 'modifier' on element 'component' is not valid with
respect to its type, 'modifierEnumType'.
----------------------------------------------------------------------------

Since the schema knows the possible values for particular attribute, Schema
based code completion should provide those values in completion list.

Thanks & Regards,
Vivek