@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"));
	}
Tests the logic of processing an environment that already contains a property source.
This test case simulates an environment with an existing property source and checks if the post-processor can interact correctly with these property sources.
spring-cloud-alibaba-starters/spring-cloud-alibaba-sentinel-gateway/src/test/java/com/alibaba/cloud/sentinel/gateway/GatewayEnvironmentPostProcessorTest.java