Bug 202236 When select NULL value for multi-value parameter, cause NPE.
Description: When select NULL value for multi-value parameter, cause NPE. Build number: 2.2.1 Steps to reproduce: 1, New a list parameter, check Allow multi-value, uncheck isRequired 2, Select parameter data type as Date 3, Add some items into list 4, Preview 5, Select Null Value item in list Expected result: Can accept Null value for multi-value parameter Actual result: Cause NPE.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/EngineTask.java
if ( paramValue instanceof Object[] )
			{
				boolean isValid = true;
				Object[] paramValueList = (Object[]) paramValue;
				for ( int i = 0; i < paramValueList.length; i++ )
				{
					if ( !validateParameterValueType( paramName,
							paramValueList[i], type, paramHandle ) )
					{
						isValid = false;
					}
				}
				return isValid;
			}
			throw new ParameterValidationException(
					MessageConstants.INVALID_PARAMETER_TYPE_EXCEPTION,
					new String[]{paramName, "Object[]",
							paramValue.getClass( ).getName( )} );
		}
		else
		{
			return validateParameterValueType( paramName, paramValue, type,
					paramHandle );
		}
	}
	
	/*
	 * Validate parameter value based on parameter type
	 */
	private boolean validateParameterValueType( String paramName,