diff --git a/spring-core/src/test/java/org/springframework/core/io/buffer/LeakAwareDataBufferFactory.java b/spring-core/src/test/java/org/springframework/core/io/buffer/LeakAwareDataBufferFactory.java
index 9c3dd02c2a23a6ab845394de48ba601fe29bf5a5..4769e3a23aa6e4208eba7f8558276afec6a5bf77 100644
--- a/spring-core/src/test/java/org/springframework/core/io/buffer/LeakAwareDataBufferFactory.java
+++ b/spring-core/src/test/java/org/springframework/core/io/buffer/LeakAwareDataBufferFactory.java
@@ -27,7 +27,6 @@ import java.util.stream.Collectors;
 import io.netty.buffer.PooledByteBufAllocator;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.jetbrains.annotations.NotNull;
 
 import org.springframework.util.Assert;
 
@@ -113,7 +112,6 @@ public class LeakAwareDataBufferFactory implements DataBufferFactory {
 		return createLeakAwareDataBuffer(this.delegate.allocateBuffer(initialCapacity));
 	}
 
-	@NotNull
 	private DataBuffer createLeakAwareDataBuffer(DataBuffer delegateBuffer) {
 		LeakAwareDataBuffer dataBuffer = new LeakAwareDataBuffer(delegateBuffer, this);
 		if (this.trackCreated.get()) {
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequest.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequest.java
index 4431499f66b5dc17bb981da4a86d5bc43f6401dd..65b65d4423725c5460ee72a82359e82b47639557 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequest.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequest.java
@@ -40,8 +40,6 @@ import javax.servlet.http.Cookie;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpSession;
 
-import org.jetbrains.annotations.NotNull;
-
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpRange;
@@ -322,7 +320,6 @@ class DefaultServerRequest implements ServerRequest {
 			this.servletRequest = servletRequest;
 		}
 
-		@NotNull
 		@Override
 		public Set<Entry<String, List<String>>> entrySet() {
 			return this.servletRequest.getParameterMap().entrySet().stream()
@@ -388,7 +385,6 @@ class DefaultServerRequest implements ServerRequest {
 			attributeNames.forEach(this.servletRequest::removeAttribute);
 		}
 
-		@NotNull
 		@Override
 		public Set<Entry<String, Object>> entrySet() {
 			return Collections.list(this.servletRequest.getAttributeNames()).stream()
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequestBuilder.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequestBuilder.java
index 762d058ccda0bedaf3f628b79c1676cea49d6bb0..cc8c44dca77ce76ba811cf361ea71d889648e15c 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequestBuilder.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequestBuilder.java
@@ -38,8 +38,6 @@ import javax.servlet.http.Cookie;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpSession;
 
-import org.jetbrains.annotations.NotNull;
-
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpInputMessage;
@@ -349,12 +347,12 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 		}
 
 		@Override
-		public int read(@NotNull byte[] b, int off, int len) throws IOException {
+		public int read(byte[] b, int off, int len) throws IOException {
 			return this.delegate.read(b, off, len);
 		}
 
 		@Override
-		public int read(@NotNull byte[] b) throws IOException {
+		public int read(byte[] b) throws IOException {
 			return this.delegate.read(b);
 		}
 
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/support/RouterFunctionMapping.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/support/RouterFunctionMapping.java
index 3aa46358d7b719645413b8c51d55a658150d1456..55dfa41e4df3035dd7647a80b3f0909d1716a6a0 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/support/RouterFunctionMapping.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/support/RouterFunctionMapping.java
@@ -23,8 +23,6 @@ import java.util.Map;
 
 import javax.servlet.http.HttpServletRequest;
 
-import org.jetbrains.annotations.NotNull;
-
 import org.springframework.beans.factory.BeanFactoryUtils;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.ApplicationContext;
@@ -167,7 +165,7 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 
 	@Nullable
 	@Override
-	protected Object getHandlerInternal(@NotNull HttpServletRequest servletRequest) throws Exception {
+	protected Object getHandlerInternal(HttpServletRequest servletRequest) throws Exception {
 		String lookupPath = getUrlPathHelper().getLookupPathForRequest(servletRequest);
 		servletRequest.setAttribute(LOOKUP_PATH, lookupPath);
 		if (this.routerFunction != null) {