Ignore non-String keys in PropertiesPropertySource.getPropertyNames()

Closes gh-32742

spring-core/src/main/java/org/springframework/core/env/PropertiesPropertySource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -48,7 +48,7 @@ public class PropertiesPropertySource extends MapPropertySource {
 	@Override
 	public String[] getPropertyNames() {
 		synchronized (this.source) {
-			return super.getPropertyNames();
+			return ((Map<?, ?>) this.source).keySet().stream().filter(k -> k instanceof String).toArray(String[]::new);
 		}
 	}
 

spring-core/src/test/java/org/springframework/core/env/StandardEnvironmentTests.java

@@ -16,7 +16,9 @@
 
 package org.springframework.core.env;
 
+import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
@@ -300,6 +302,12 @@ class StandardEnvironmentTests {
 			assertThat(systemProperties.get(DISALLOWED_PROPERTY_NAME)).isEqualTo(DISALLOWED_PROPERTY_VALUE);
 			assertThat(systemProperties.get(STRING_PROPERTY_NAME)).isEqualTo(NON_STRING_PROPERTY_VALUE);
 			assertThat(systemProperties.get(NON_STRING_PROPERTY_NAME)).isEqualTo(STRING_PROPERTY_VALUE);
+
+			PropertiesPropertySource systemPropertySource = (PropertiesPropertySource)
+					environment.getPropertySources().get(StandardEnvironment.SYSTEM_PROPERTIES_PROPERTY_SOURCE_NAME);
+			Set<String> expectedKeys = new HashSet<>(System.getProperties().stringPropertyNames());
+			expectedKeys.add(STRING_PROPERTY_NAME);  // filtered out by stringPropertyNames due to non-String value
+			assertThat(Set.of(systemPropertySource.getPropertyNames())).isEqualTo(expectedKeys);
 		}
 		finally {
 			System.clearProperty(ALLOWED_PROPERTY_NAME);
@@ -316,6 +324,7 @@ class StandardEnvironmentTests {
 		assertThat(System.getenv()).isSameAs(systemEnvironment);
 	}
 
+
 	@Nested
 	class GetActiveProfiles {
 
@@ -365,6 +374,7 @@ class StandardEnvironmentTests {
 		}
 	}
 
+
 	@Nested
 	class AcceptsProfilesTests {
 
@@ -447,9 +457,9 @@ class StandardEnvironmentTests {
 			environment.addActiveProfile("p2");
 			assertThat(environment.acceptsProfiles(Profiles.of("p1 & p2"))).isTrue();
 		}
-
 	}
 
+
 	@Nested
 	class MatchesProfilesTests {
 
@@ -549,7 +559,6 @@ class StandardEnvironmentTests {
 			assertThat(environment.matchesProfiles("p2 & (foo | p1)")).isTrue();
 			assertThat(environment.matchesProfiles("foo", "(p2 & p1)")).isTrue();
 		}
-
 	}
 
 }