diff --git a/spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/LocalDevToolsAutoConfiguration.java b/spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/LocalDevToolsAutoConfiguration.java
index 820d6eea7fd..5dd40c6df31 100644
--- a/spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/LocalDevToolsAutoConfiguration.java
+++ b/spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/LocalDevToolsAutoConfiguration.java
@@ -42,7 +42,6 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.context.event.ContextRefreshedEvent;
 import org.springframework.context.event.GenericApplicationListener;
 import org.springframework.core.ResolvableType;
-import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
 /**
@@ -185,7 +184,7 @@ public class LocalDevToolsAutoConfiguration {
 		}
 
 		@Override
-		public boolean supportsSourceType(@Nullable Class<?> sourceType) {
+		public boolean supportsSourceType(Class<?> sourceType) {
 			return true;
 		}
 
diff --git a/spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/reactive/webclient/ExampleIdConverter.java b/spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/reactive/webclient/ExampleIdConverter.java
index 9cc7ad7a500..d7912e26f1e 100644
--- a/spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/reactive/webclient/ExampleIdConverter.java
+++ b/spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/reactive/webclient/ExampleIdConverter.java
@@ -23,7 +23,6 @@ import java.util.UUID;
 import org.springframework.boot.test.autoconfigure.web.reactive.WebFluxTest;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.converter.GenericConverter;
-import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Component;
 
 /**
@@ -39,9 +38,8 @@ public class ExampleIdConverter implements GenericConverter {
 		return Collections.singleton(new ConvertiblePair(String.class, ExampleId.class));
 	}
 
-	@Nullable
 	@Override
-	public Object convert(@Nullable Object source, TypeDescriptor sourceType,
+	public Object convert(Object source, TypeDescriptor sourceType,
 			TypeDescriptor targetType) {
 		if (source == null) {
 			return null;
diff --git a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/admin/SpringApplicationAdminMXBeanRegistrar.java b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/admin/SpringApplicationAdminMXBeanRegistrar.java
index 732b454ba4a..b0d11b79c8c 100644
--- a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/admin/SpringApplicationAdminMXBeanRegistrar.java
+++ b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/admin/SpringApplicationAdminMXBeanRegistrar.java
@@ -40,7 +40,6 @@ import org.springframework.core.Ordered;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.env.Environment;
 import org.springframework.core.env.StandardEnvironment;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -95,7 +94,7 @@ public class SpringApplicationAdminMXBeanRegistrar implements ApplicationContext
 	}
 
 	@Override
-	public boolean supportsSourceType(@Nullable Class<?> sourceType) {
+	public boolean supportsSourceType(Class<?> sourceType) {
 		return true;
 	}
 
diff --git a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/ArrayToDelimitedStringConverter.java b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/ArrayToDelimitedStringConverter.java
index d457d6f345f..4c2d9b18c89 100644
--- a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/ArrayToDelimitedStringConverter.java
+++ b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/ArrayToDelimitedStringConverter.java
@@ -24,7 +24,6 @@ import java.util.Set;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.converter.ConditionalGenericConverter;
-import org.springframework.lang.Nullable;
 import org.springframework.util.ObjectUtils;
 
 /**
@@ -51,8 +50,7 @@ final class ArrayToDelimitedStringConverter implements ConditionalGenericConvert
 	}
 
 	@Override
-	@Nullable
-	public Object convert(@Nullable Object source, TypeDescriptor sourceType,
+	public Object convert(Object source, TypeDescriptor sourceType,
 			TypeDescriptor targetType) {
 		List<Object> list = Arrays.asList(ObjectUtils.toObjectArray(source));
 		return this.delegate.convert(list, sourceType, targetType);
diff --git a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/DelimitedStringToArrayConverter.java b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/DelimitedStringToArrayConverter.java
index 581946fa544..9f5b4ea7fe3 100644
--- a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/DelimitedStringToArrayConverter.java
+++ b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/DelimitedStringToArrayConverter.java
@@ -23,7 +23,6 @@ import java.util.Set;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.converter.ConditionalGenericConverter;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -53,8 +52,7 @@ final class DelimitedStringToArrayConverter implements ConditionalGenericConvert
 	}
 
 	@Override
-	@Nullable
-	public Object convert(@Nullable Object source, TypeDescriptor sourceType,
+	public Object convert(Object source, TypeDescriptor sourceType,
 			TypeDescriptor targetType) {
 		if (source == null) {
 			return null;
diff --git a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/DelimitedStringToCollectionConverter.java b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/DelimitedStringToCollectionConverter.java
index 0b7670f5193..746dc7e7b39 100644
--- a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/DelimitedStringToCollectionConverter.java
+++ b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/DelimitedStringToCollectionConverter.java
@@ -26,7 +26,6 @@ import org.springframework.core.CollectionFactory;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.converter.ConditionalGenericConverter;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -56,8 +55,7 @@ final class DelimitedStringToCollectionConverter implements ConditionalGenericCo
 	}
 
 	@Override
-	@Nullable
-	public Object convert(@Nullable Object source, TypeDescriptor sourceType,
+	public Object convert(Object source, TypeDescriptor sourceType,
 			TypeDescriptor targetType) {
 		if (source == null) {
 			return null;
diff --git a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java
index e6f82836995..971d8d54c24 100644
--- a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java
+++ b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java
@@ -66,7 +66,6 @@ import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.ProtocolResolver;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
-import org.springframework.lang.Nullable;
 import org.springframework.mock.env.MockEnvironment;
 import org.springframework.stereotype.Component;
 import org.springframework.test.context.support.TestPropertySourceUtils;
@@ -1785,7 +1784,6 @@ public class ConfigurationPropertiesTests {
 
 	static class PersonConverter implements Converter<String, Person> {
 
-		@Nullable
 		@Override
 		public Person convert(String source) {
 			String[] content = StringUtils.split(source, " ");
@@ -1796,15 +1794,13 @@ public class ConfigurationPropertiesTests {
 
 	static class GenericPersonConverter implements GenericConverter {
 
-		@Nullable
 		@Override
 		public Set<ConvertiblePair> getConvertibleTypes() {
 			return Collections.singleton(new ConvertiblePair(String.class, Person.class));
 		}
 
-		@Nullable
 		@Override
-		public Object convert(@Nullable Object source, TypeDescriptor sourceType,
+		public Object convert(Object source, TypeDescriptor sourceType,
 				TypeDescriptor targetType) {
 			String[] content = StringUtils.split((String) source, " ");
 			return new Person(content[0], content[1]);