Bug 198917 set __parameterpage to false for required parameter will cause wrong Exception[0705]
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/EngineTask.java
throw new ParameterValidationException(
					MessageConstants.INVALID_PARAMETER_TYPE_EXCEPTION,
					new String[]{paramName, type, "Date"} );
		}
		else if ( DesignChoiceConstants.PARAM_TYPE_TIME.equals( type ) )
		{
			if ( paramValue instanceof java.sql.Time )
				return true;
			throw new ParameterValidationException(
					MessageConstants.INVALID_PARAMETER_TYPE_EXCEPTION,
					new String[]{paramName, type, "Time"} );
		}
		else if ( DesignChoiceConstants.PARAM_TYPE_STRING.equals( type ) )
		{
			String value = paramValue.toString( ).trim( );
			if ( paramHandle.isRequired( ) && value.equals( "" ) ) 
			{
				throw new ParameterValidationException(
						MessageConstants.INVALID_PARAMETER_TYPE_EXCEPTION,
						new String[]{paramName, type, "String"} );
			}
			return true;
		}
		else if ( DesignChoiceConstants.PARAM_TYPE_BOOLEAN.equals( type ) )
		{
			if ( paramValue instanceof Boolean )
				return true;
			throw new ParameterValidationException(
					MessageConstants.INVALID_PARAMETER_TYPE_EXCEPTION,
					new String[]{paramName, type, "Boolean"} );