@Test
	public void testPostProcessEnvironment() {
		ConfigurableEnvironment environment = mock(ConfigurableEnvironment.class);
		MutablePropertySources propertySources = new MutablePropertySources();
		when(environment.getPropertySources()).thenReturn(propertySources);

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

		PropertySource<?> propertySource = propertySources.get("defaultProperties");
		Assert.assertNotNull(propertySource);
		Assert.assertNotNull(propertySource.getProperty("spring.cloud.sentinel.filter.enabled"));
	}
Tests the custom property source processing logic.
This test case verifies whether the custom property source is correctly added during the environment post-processing.
Specifically, it checks if the configuration property "spring.cloud.sentinel.filter.enabled" is properly added.
spring-cloud-alibaba-starters/spring-cloud-alibaba-sentinel-gateway/src/test/java/com/alibaba/cloud/sentinel/gateway/GatewayEnvironmentPostProcessorTest.java