@Override
	public void postProcessEnvironment(ConfigurableEnvironment environment,
			SpringApplication springApplication) {
		addDefaultPropertySource(environment);
	}
@Test
	public void testPostProcessEnvironmentWithExistingPropertySource() {
		ConfigurableEnvironment environment = mock(ConfigurableEnvironment.class);
		MutablePropertySources propertySources = new MutablePropertySources();
		when(environment.getPropertySources()).thenReturn(propertySources);

		Map<String, Object> existingProperties = new HashMap<>();
		existingProperties.put("existing.property", "value");
		MapPropertySource existingPropertySource = new MapPropertySource("defaultProperties", existingProperties);
		propertySources.addFirst(existingPropertySource);

		GatewayEnvironmentPostProcessor postProcessor = new GatewayEnvironmentPostProcessor();
		postProcessor.postProcessEnvironment(environment, mock(SpringApplication.class));

		PropertySource<?> propertySource = propertySources.get("defaultProperties");
		Assert.assertNotNull(propertySource);
		Assert.assertEquals("value", propertySource.getProperty("existing.property"));
		Assert.assertEquals("false", propertySource.getProperty("spring.cloud.sentinel.filter.enabled"));
	}