diff --git a/spring-core/src/main/java/org/springframework/core/env/MutablePropertySources.java b/spring-core/src/main/java/org/springframework/core/env/MutablePropertySources.java
index 1fa383b38d93..1bc07bc7b542 100644
--- a/spring-core/src/main/java/org/springframework/core/env/MutablePropertySources.java
+++ b/spring-core/src/main/java/org/springframework/core/env/MutablePropertySources.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -79,14 +79,23 @@ public Stream<PropertySource<?>> stream() {
 
 	@Override
 	public boolean contains(String name) {
-		return this.propertySourceList.contains(PropertySource.named(name));
+		for (PropertySource<?> propertySource : this.propertySourceList) {
+			if (propertySource.getName().equals(name)) {
+				return true;
+			}
+		}
+		return false;
 	}
 
 	@Override
 	@Nullable
 	public PropertySource<?> get(String name) {
-		int index = this.propertySourceList.indexOf(PropertySource.named(name));
-		return (index != -1 ? this.propertySourceList.get(index) : null);
+		for (PropertySource<?> propertySource : this.propertySourceList) {
+			if (propertySource.getName().equals(name)) {
+				return propertySource;
+			}
+		}
+		return null;
 	}
 
 
@@ -94,16 +103,20 @@ public PropertySource<?> get(String name) {
 	 * Add the given property source object with highest precedence.
 	 */
 	public void addFirst(PropertySource<?> propertySource) {
-		removeIfPresent(propertySource);
-		this.propertySourceList.add(0, propertySource);
+		synchronized (this.propertySourceList) {
+			removeIfPresent(propertySource);
+			this.propertySourceList.add(0, propertySource);
+		}
 	}
 
 	/**
 	 * Add the given property source object with lowest precedence.
 	 */
 	public void addLast(PropertySource<?> propertySource) {
-		removeIfPresent(propertySource);
-		this.propertySourceList.add(propertySource);
+		synchronized (this.propertySourceList) {
+			removeIfPresent(propertySource);
+			this.propertySourceList.add(propertySource);
+		}
 	}
 
 	/**
@@ -112,9 +125,11 @@ public void addLast(PropertySource<?> propertySource) {
 	 */
 	public void addBefore(String relativePropertySourceName, PropertySource<?> propertySource) {
 		assertLegalRelativeAddition(relativePropertySourceName, propertySource);
-		removeIfPresent(propertySource);
-		int index = assertPresentAndGetIndex(relativePropertySourceName);
-		addAtIndex(index, propertySource);
+		synchronized (this.propertySourceList) {
+			removeIfPresent(propertySource);
+			int index = assertPresentAndGetIndex(relativePropertySourceName);
+			addAtIndex(index, propertySource);
+		}
 	}
 
 	/**
@@ -123,9 +138,11 @@ public void addBefore(String relativePropertySourceName, PropertySource<?> prope
 	 */
 	public void addAfter(String relativePropertySourceName, PropertySource<?> propertySource) {
 		assertLegalRelativeAddition(relativePropertySourceName, propertySource);
-		removeIfPresent(propertySource);
-		int index = assertPresentAndGetIndex(relativePropertySourceName);
-		addAtIndex(index + 1, propertySource);
+		synchronized (this.propertySourceList) {
+			removeIfPresent(propertySource);
+			int index = assertPresentAndGetIndex(relativePropertySourceName);
+			addAtIndex(index + 1, propertySource);
+		}
 	}
 
 	/**
@@ -141,8 +158,10 @@ public int precedenceOf(PropertySource<?> propertySource) {
 	 */
 	@Nullable
 	public PropertySource<?> remove(String name) {
-		int index = this.propertySourceList.indexOf(PropertySource.named(name));
-		return (index != -1 ? this.propertySourceList.remove(index) : null);
+		synchronized (this.propertySourceList) {
+			int index = this.propertySourceList.indexOf(PropertySource.named(name));
+			return (index != -1 ? this.propertySourceList.remove(index) : null);
+		}
 	}
 
 	/**
@@ -153,8 +172,10 @@ public PropertySource<?> remove(String name) {
 	 * @see #contains
 	 */
 	public void replace(String name, PropertySource<?> propertySource) {
-		int index = assertPresentAndGetIndex(name);
-		this.propertySourceList.set(index, propertySource);
+		synchronized (this.propertySourceList) {
+			int index = assertPresentAndGetIndex(name);
+			this.propertySourceList.set(index, propertySource);
+		}
 	}
 
 	/**
@@ -169,6 +190,7 @@ public String toString() {
 		return this.propertySourceList.toString();
 	}
 
+
 	/**
 	 * Ensure that the given property source is not being added relative to itself.
 	 */
diff --git a/spring-core/src/main/java/org/springframework/core/env/PropertySource.java b/spring-core/src/main/java/org/springframework/core/env/PropertySource.java
index 112fc1350bfe..68eda2f70bcc 100644
--- a/spring-core/src/main/java/org/springframework/core/env/PropertySource.java
+++ b/spring-core/src/main/java/org/springframework/core/env/PropertySource.java
@@ -136,7 +136,7 @@ public boolean containsProperty(String name) {
 	@Override
 	public boolean equals(Object other) {
 		return (this == other || (other instanceof PropertySource &&
-				ObjectUtils.nullSafeEquals(this.name, ((PropertySource<?>) other).name)));
+				ObjectUtils.nullSafeEquals(getName(), ((PropertySource<?>) other).getName())));
 	}
 
 	/**
@@ -145,7 +145,7 @@ public boolean equals(Object other) {
 	 */
 	@Override
 	public int hashCode() {
-		return ObjectUtils.nullSafeHashCode(this.name);
+		return ObjectUtils.nullSafeHashCode(getName());
 	}
 
 	/**
@@ -161,10 +161,10 @@ public int hashCode() {
 	public String toString() {
 		if (logger.isDebugEnabled()) {
 			return getClass().getSimpleName() + "@" + System.identityHashCode(this) +
-					" {name='" + this.name + "', properties=" + this.source + "}";
+					" {name='" + getName() + "', properties=" + getSource() + "}";
 		}
 		else {
-			return getClass().getSimpleName() + " {name='" + this.name + "'}";
+			return getClass().getSimpleName() + " {name='" + getName() + "'}";
 		}
 	}
 
diff --git a/spring-web/src/main/java/org/springframework/web/context/support/WebApplicationContextUtils.java b/spring-web/src/main/java/org/springframework/web/context/support/WebApplicationContextUtils.java
index 73da6c9e9028..d9bfe57b1523 100644
--- a/spring-web/src/main/java/org/springframework/web/context/support/WebApplicationContextUtils.java
+++ b/spring-web/src/main/java/org/springframework/web/context/support/WebApplicationContextUtils.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -296,11 +296,11 @@ public static void initServletPropertySources(MutablePropertySources sources,
 
 		Assert.notNull(sources, "'propertySources' must not be null");
 		String name = StandardServletEnvironment.SERVLET_CONTEXT_PROPERTY_SOURCE_NAME;
-		if (servletContext != null && sources.contains(name) && sources.get(name) instanceof StubPropertySource) {
+		if (servletContext != null && sources.get(name) instanceof StubPropertySource) {
 			sources.replace(name, new ServletContextPropertySource(name, servletContext));
 		}
 		name = StandardServletEnvironment.SERVLET_CONFIG_PROPERTY_SOURCE_NAME;
-		if (servletConfig != null && sources.contains(name) && sources.get(name) instanceof StubPropertySource) {
+		if (servletConfig != null && sources.get(name) instanceof StubPropertySource) {
 			sources.replace(name, new ServletConfigPropertySource(name, servletConfig));
 		}
 	}