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.NULL_PARAMETER_EXCEPTION,
						new String[]{paramName, source} );
			}
		}
		
		/*
		 * Validate based on parameter type
		 */
		if ( DesignChoiceConstants.PARAM_TYPE_DECIMAL.equals( type )
				|| DesignChoiceConstants.PARAM_TYPE_FLOAT.equals( type ) )
		{
			if ( paramValue instanceof Number )
				return true;
			throw new ParameterValidationException(
					MessageConstants.INVALID_PARAMETER_TYPE_EXCEPTION,
					new String[]{paramName, type, "Float or BigDecimal"} );
		}
		else if ( DesignChoiceConstants.PARAM_TYPE_DATETIME.equals( type ) )
		{
			if ( paramValue instanceof Date )
				return true;
			throw new ParameterValidationException(
					MessageConstants.INVALID_PARAMETER_TYPE_EXCEPTION,
					new String[]{paramName, type, "DateTime"} );
		}
		else if ( DesignChoiceConstants.PARAM_TYPE_DATE.equals( type ) )
		{
			if ( paramValue instanceof java.sql.Date )
				return true;