multiplicity with 1 for simple type generate wrong code in Reader/Writer

[slawekjaranowski]

Eg for field type of String we have used method like:

• parseString
• writeString
• updateString

which is not defined

to reproduce use:

        <field>
          <name>listField</name>
          <type>List</type>
          <association>
            <type>String</type>
            <multiplicity>1</multiplicity>
          </association>
        </field>