To fully document this interceptor, it is best to look at the JavaDocs for the subclass of the interceptor, ConversionErrorInterceptor:
This interceptor adds any error found in the ActionContext's conversionErrors map as a field error (provided
that the action implements ValidationAware). In addition, any field that contains a validation error has its
original value saved such that any subsequent requests for that value return the original value rather than the value
in the action. This is important because if the value "abc" is submitted and can't be converted to an int, we want to
display the original string ("abc") again rather than the int value (likely 0, which would make very little sense to
the user).
... as well as the JavaDocs for the interceptor itself, WebWorkConversionErrorInterceptor:
This interceptor extends ConversionErrorInterceptor but only adds conversion errors from the ActionContext to
the field errors of the action if the field value is not null, "", or {""} (a size 1 String array with only an empty
String). See ConversionErrorInterceptor for more information, as well as the Type Conversion documentation.
Parameters
Extending the Interceptor
There are no known extension points for this interceptor.
Examples
<action name="someAction" class="com.examples.SomeAction">
<interceptor-ref name="params"/>
<interceptor-ref name="conversionError"/>
<result name="success">good_result.ftl</result>
</action>
