Bug 203909 If a parameter have no default value, the value of parameter in computed column should not be "null"[07]
Description: If a parameter have no default value, the value of parameter in computed column should not be "null"[07] Build number: 2.2.1.v20070918-0630 Steps to reproduce: 1, New a String type parameter and left the default value empty 2, New a Dataset and new a computed column 3, Specify the expression to params["parameterName"] 4, Preview in dataset Expected result: The value should not be "null" but blank Actual result: The value of computed column is "null"
data/org.eclipse.birt.report.data.adapter/src/org/eclipse/birt/report/data/adapter/api/script/DataAdapterTopLevelScope.java
* @param module Module associated with this scope; can be null
	 */
	public DataAdapterTopLevelScope( Context cx, ModuleHandle module )
	{
		super(cx);
		
		new CoreJavaScriptInitializer( ).initialize( cx, this );
		designModule = module;
	}
	
    public boolean has(String name, Scriptable start) 
    {
    	if ( super.has(name, start) )
    		return true;
    	
    	if ( designModule != null && PROP_PARAMS.equals(name) )
    		return true;
    	
    	if ( PROP_REPORTCONTEXT.equals( name ) )
			return true;
    	return false;
    }
    public Object get(String name, Scriptable start) 
    {
        Object result = super.get(name, start);
        if (result != NOT_FOUND)
            return result;
        
    	if ( designModule != null && PROP_PARAMS.equals(name) )
    	{