few improvements of generation xsd for dynamic types with compound properties

1. There is class cast exception in
org.apache.tuscany.sdo.helper.SchemaBuilder.handleBaseExtn(XSDSchema, Type, XSDComplexTypeDefinition).

2. Some time generated XSD schema is incomplete.
use case:
1. Define dynamic type with more than one compound properties defined as dynamic types as well.
2. call XSDHelper.generate(type).
3. Resulting XSD include xs:complexType defs for compound properties. But some of them may be empty, i.e.:
<xs:complexType abstract="false" name="compound_property_type_name" />
instead of
<xs:complexType abstract="false" name="compound_property_type_name" >
<xs:sequence>
...
</xs:complexType>
It seems that problem is incorrect API usage in
org.apache.tuscany.sdo.helper.SchemaBuilder.buildComplexSchemaType(Type):

Patch to resolve both problems:

Index: SchemaBuilder.java
===================================================================
— SchemaBuilder.java (revision 149)
+++ SchemaBuilder.java (revision 150)
@@ -338,7 +338,7 @@
complexType.setTargetNamespace(targetNamespace);
complexType.setAbstract(dataType.isAbstract());

• xmlSchema.getTypeDefinitions().add(complexType);
  + //xmlSchema.getTypeDefinitions().add(complexType);
  xmlSchema.getContents().add(complexType);

complexType.updateElement();
@@ -730,7 +730,7 @@
}
else

{ - complexType.setBaseTypeDefinition((XSDSimpleTypeDefinition)typeTable. + complexType.setBaseTypeDefinition((XSDComplexTypeDefinition)typeTable. getXSDTypeDef(baseSchemaType.getNamespaceURI(),baseSchemaType.getLocalPart())); }