Add nullability annotations to core/spring-boot-properties-migrator

See gh-46587

Author: mhalbritter

core/spring-boot-properties-migrator/src/main/java/org/springframework/boot/context/properties/migrator/PropertiesMigrationListener.java

@@ -21,6 +21,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.configurationmetadata.ConfigurationMetadataRepository;
 import org.springframework.boot.configurationmetadata.ConfigurationMetadataRepositoryJsonBuilder;
@@ -44,7 +45,7 @@ class PropertiesMigrationListener implements ApplicationListener<SpringApplicati
 
 	private static final Log logger = LogFactory.getLog(PropertiesMigrationListener.class);
 
-	private PropertiesMigrationReport report;
+	private @Nullable PropertiesMigrationReport report;
 
 	private boolean reported;
 

core/spring-boot-properties-migrator/src/main/java/org/springframework/boot/context/properties/migrator/PropertiesMigrationReport.java

@@ -23,6 +23,8 @@
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Provides a properties migration report.
  *
@@ -38,7 +40,7 @@ class PropertiesMigrationReport {
 	 * properties were found, return {@code null}.
 	 * @return a report with the configurations keys that should be renamed
 	 */
-	String getWarningReport() {
+	@Nullable String getWarningReport() {
 		Map<String, List<PropertyMigration>> content = getContent(LegacyProperties::getRenamed);
 		if (content.isEmpty()) {
 			return null;
@@ -60,7 +62,7 @@ String getWarningReport() {
 	 * properties were found, return {@code null}.
 	 * @return a report with the configurations keys that are no longer supported
 	 */
-	String getErrorReport() {
+	@Nullable String getErrorReport() {
 		Map<String, List<PropertyMigration>> content = getContent(LegacyProperties::getUnsupported);
 		if (content.isEmpty()) {
 			return null;

core/spring-boot-properties-migrator/src/main/java/org/springframework/boot/context/properties/migrator/PropertiesMigrationReporter.java

@@ -26,6 +26,8 @@
 import java.util.Set;
 import java.util.function.Predicate;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.configurationmetadata.ConfigurationMetadataProperty;
 import org.springframework.boot.configurationmetadata.ConfigurationMetadataRepository;
 import org.springframework.boot.context.properties.source.ConfigurationProperty;
@@ -38,6 +40,7 @@
 import org.springframework.boot.origin.PropertySourceOrigin;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.PropertySource;
+import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
@@ -109,7 +112,9 @@ private String determinePropertySourceName(ConfigurationPropertySource source) {
 		if (source.getUnderlyingSource() instanceof PropertySource<?> underlyingSource) {
 			return underlyingSource.getName();
 		}
-		return source.getUnderlyingSource().toString();
+		Object underlyingSource = source.getUnderlyingSource();
+		Assert.state(underlyingSource != null, "'underlyingSource' must not be null");
+		return underlyingSource.toString();
 	}
 
 	private List<PropertyMigration> getMigrations(ConfigurationPropertySource propertySource,
@@ -149,7 +154,8 @@ private boolean hasSameName(ConfigurationProperty property, ConfigurationMetadat
 				&& Objects.equals(propertySourceOrigin.getPropertyName(), replacement.getId());
 	}
 
-	private ConfigurationMetadataProperty determineReplacementMetadata(ConfigurationMetadataProperty metadata) {
+	private @Nullable ConfigurationMetadataProperty determineReplacementMetadata(
+			ConfigurationMetadataProperty metadata) {
 		String replacementId = metadata.getDeprecation().getReplacement();
 		if (StringUtils.hasText(replacementId)) {
 			ConfigurationMetadataProperty replacement = this.allProperties.get(replacementId);
@@ -161,7 +167,7 @@ private ConfigurationMetadataProperty determineReplacementMetadata(Configuration
 		return null;
 	}
 
-	private ConfigurationMetadataProperty detectMapValueReplacement(String fullId) {
+	private @Nullable ConfigurationMetadataProperty detectMapValueReplacement(String fullId) {
 		int lastDot = fullId.lastIndexOf('.');
 		if (lastDot == -1) {
 			return null;
@@ -178,7 +184,7 @@ private boolean isMapType(ConfigurationMetadataProperty property) {
 		return type != null && type.startsWith(Map.class.getName());
 	}
 
-	private PropertySource<?> mapPropertiesWithReplacement(PropertiesMigrationReport report, String name,
+	private @Nullable PropertySource<?> mapPropertiesWithReplacement(PropertiesMigrationReport report, String name,
 			List<PropertyMigration> properties) {
 		report.add(name, properties);
 		List<PropertyMigration> renamed = properties.stream().filter(PropertyMigration::isCompatibleType).toList();
@@ -229,7 +235,7 @@ boolean isPlaceholderThatAccessesName(Object value, String name) {
 		}
 
 		@Override
-		public Object getProperty(String name) {
+		public @Nullable Object getProperty(String name) {
 			this.accessedNames.add(name);
 			return null;
 		}

core/spring-boot-properties-migrator/src/main/java/org/springframework/boot/context/properties/migrator/PropertyMigration.java

@@ -20,6 +20,8 @@
 import java.util.Comparator;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.configurationmetadata.ConfigurationMetadataProperty;
 import org.springframework.boot.configurationmetadata.Deprecation;
 import org.springframework.boot.context.properties.source.ConfigurationProperty;
@@ -43,11 +45,11 @@ class PropertyMigration {
 
 	private final ConfigurationProperty property;
 
-	private final Integer lineNumber;
+	private final @Nullable Integer lineNumber;
 
 	private final ConfigurationMetadataProperty metadata;
 
-	private final ConfigurationMetadataProperty replacementMetadata;
+	private final @Nullable ConfigurationMetadataProperty replacementMetadata;
 
 	/**
 	 * Whether this migration happened from a map type.
@@ -57,7 +59,7 @@ class PropertyMigration {
 	private final boolean compatibleType;
 
 	PropertyMigration(ConfigurationProperty property, ConfigurationMetadataProperty metadata,
-			ConfigurationMetadataProperty replacementMetadata, boolean mapMigration) {
+			@Nullable ConfigurationMetadataProperty replacementMetadata, boolean mapMigration) {
 		this.property = property;
 		this.lineNumber = determineLineNumber(property);
 		this.metadata = metadata;
@@ -66,7 +68,7 @@ class PropertyMigration {
 		this.compatibleType = determineCompatibleType(metadata, replacementMetadata);
 	}
 
-	private static Integer determineLineNumber(ConfigurationProperty property) {
+	private static @Nullable Integer determineLineNumber(ConfigurationProperty property) {
 		Origin origin = property.getOrigin();
 		if (origin instanceof PropertySourceOrigin propertySourceOrigin) {
 			origin = propertySourceOrigin.getOrigin();
@@ -80,7 +82,7 @@ private static Integer determineLineNumber(ConfigurationProperty property) {
 	}
 
 	private static boolean determineCompatibleType(ConfigurationMetadataProperty metadata,
-			ConfigurationMetadataProperty replacementMetadata) {
+			@Nullable ConfigurationMetadataProperty replacementMetadata) {
 		String currentType = determineType(metadata);
 		String replacementType = determineType(replacementMetadata);
 		if (currentType == null || replacementType == null) {
@@ -93,7 +95,7 @@ private static boolean determineCompatibleType(ConfigurationMetadataProperty met
 				&& (currentType.equals(Long.class.getName()) || currentType.equals(Integer.class.getName()));
 	}
 
-	private static String determineType(ConfigurationMetadataProperty metadata) {
+	private static @Nullable String determineType(@Nullable ConfigurationMetadataProperty metadata) {
 		if (metadata == null || metadata.getType() == null) {
 			return null;
 		}
@@ -112,7 +114,7 @@ ConfigurationProperty getProperty() {
 		return this.property;
 	}
 
-	Integer getLineNumber() {
+	@Nullable Integer getLineNumber() {
 		return this.lineNumber;
 	}
 
@@ -126,7 +128,9 @@ boolean isCompatibleType() {
 
 	String getNewPropertyName() {
 		if (this.mapMigration) {
-			return getNewMapPropertyName(this.property, this.metadata, this.replacementMetadata).toString();
+			ConfigurationMetadataProperty replacementMetadata = this.replacementMetadata;
+			Assert.state(replacementMetadata != null, "'replacementMetadata' must not be null");
+			return getNewMapPropertyName(this.property, this.metadata, replacementMetadata).toString();
 		}
 		return this.metadata.getDeprecation().getReplacement();
 	}

core/spring-boot-properties-migrator/src/main/java/org/springframework/boot/context/properties/migrator/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Support for migrating legacy Spring Boot properties.
  */
+@NullMarked
 package org.springframework.boot.context.properties.migrator;
+
+import org.jspecify.annotations.NullMarked;