Add nullability annotations to module/spring-boot-mustache

See gh-46587

Author: mhalbritter

module/spring-boot-mustache/src/main/java/org/springframework/boot/mustache/autoconfigure/MustacheProperties.java

@@ -23,6 +23,8 @@
 import java.util.Map;
 import java.util.function.Supplier;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.http.MediaType;
 import org.springframework.util.MimeType;
@@ -51,12 +53,12 @@ public class MustacheProperties {
 	/**
 	 * View names that can be resolved.
 	 */
-	private String[] viewNames;
+	private String @Nullable [] viewNames;
 
 	/**
 	 * Name of the RequestContext attribute for all views.
 	 */
-	private String requestContextAttribute;
+	private @Nullable String requestContextAttribute;
 
 	/**
 	 * Whether to enable MVC view resolution for Mustache.
@@ -107,19 +109,19 @@ public void setSuffix(String suffix) {
 		this.suffix = suffix;
 	}
 
-	public String[] getViewNames() {
+	public String @Nullable [] getViewNames() {
 		return this.viewNames;
 	}
 
-	public void setViewNames(String[] viewNames) {
+	public void setViewNames(String @Nullable [] viewNames) {
 		this.viewNames = viewNames;
 	}
 
-	public String getRequestContextAttribute() {
+	public @Nullable String getRequestContextAttribute() {
 		return this.requestContextAttribute;
 	}
 
-	public void setRequestContextAttribute(String requestContextAttribute) {
+	public void setRequestContextAttribute(@Nullable String requestContextAttribute) {
 		this.requestContextAttribute = requestContextAttribute;
 	}
 
@@ -128,7 +130,7 @@ public Charset getCharset() {
 	}
 
 	public String getCharsetName() {
-		return (this.charset != null) ? this.charset.name() : null;
+		return this.charset.name();
 	}
 
 	public void setCharset(Charset charset) {
@@ -275,13 +277,13 @@ public static class Reactive {
 		/**
 		 * Media types supported by Mustache views.
 		 */
-		private List<MediaType> mediaTypes;
+		private @Nullable List<MediaType> mediaTypes;
 
-		public List<MediaType> getMediaTypes() {
+		public @Nullable List<MediaType> getMediaTypes() {
 			return this.mediaTypes;
 		}
 
-		public void setMediaTypes(List<MediaType> mediaTypes) {
+		public void setMediaTypes(@Nullable List<MediaType> mediaTypes) {
 			this.mediaTypes = mediaTypes;
 		}
 

module/spring-boot-mustache/src/main/java/org/springframework/boot/mustache/autoconfigure/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Auto-configuration for Mustache.
  */
+@NullMarked
 package org.springframework.boot.mustache.autoconfigure;
+
+import org.jspecify.annotations.NullMarked;

module/spring-boot-mustache/src/main/java/org/springframework/boot/mustache/reactive/view/MustacheView.java

@@ -28,14 +28,17 @@
 
 import com.samskivert.mustache.Mustache.Compiler;
 import com.samskivert.mustache.Template;
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
+import org.springframework.context.ApplicationContext;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferUtils;
 import org.springframework.core.io.buffer.DefaultDataBufferFactory;
 import org.springframework.http.MediaType;
+import org.springframework.util.Assert;
 import org.springframework.web.reactive.result.view.AbstractUrlBasedView;
 import org.springframework.web.reactive.result.view.View;
 import org.springframework.web.server.ServerWebExchange;
@@ -48,9 +51,9 @@
  */
 public class MustacheView extends AbstractUrlBasedView {
 
-	private Compiler compiler;
+	private @Nullable Compiler compiler;
 
-	private String charset;
+	private @Nullable String charset;
 
 	/**
 	 * Set the JMustache compiler to be used by this view. Typically this property is not
@@ -66,7 +69,7 @@ public void setCompiler(Compiler compiler) {
 	 * Set the charset used for reading Mustache template files.
 	 * @param charset the charset to use for reading template files
 	 */
-	public void setCharset(String charset) {
+	public void setCharset(@Nullable String charset) {
 		this.charset = charset;
 	}
 
@@ -76,7 +79,8 @@ public boolean checkResourceExists(Locale locale) throws Exception {
 	}
 
 	@Override
-	protected Mono<Void> renderInternal(Map<String, Object> model, MediaType contentType, ServerWebExchange exchange) {
+	protected Mono<Void> renderInternal(Map<String, Object> model, @Nullable MediaType contentType,
+			ServerWebExchange exchange) {
 		Resource resource = resolveResource();
 		if (resource == null) {
 			return Mono
@@ -86,6 +90,7 @@ protected Mono<Void> renderInternal(Map<String, Object> model, MediaType content
 			.bufferFactory()
 			.allocateBuffer(DefaultDataBufferFactory.DEFAULT_INITIAL_CAPACITY);
 		try (Reader reader = getReader(resource)) {
+			Assert.state(this.compiler != null, "'compiler' must not be null");
 			Template template = this.compiler.compile(reader);
 			Charset charset = getCharset(contentType).orElseGet(this::getDefaultCharset);
 			try (Writer writer = new OutputStreamWriter(dataBuffer.asOutputStream(), charset)) {
@@ -100,8 +105,13 @@ protected Mono<Void> renderInternal(Map<String, Object> model, MediaType content
 		return exchange.getResponse().writeWith(Flux.just(dataBuffer));
 	}
 
-	private Resource resolveResource() {
-		Resource resource = getApplicationContext().getResource(getUrl());
+	private @Nullable Resource resolveResource() {
+		ApplicationContext applicationContext = getApplicationContext();
+		String url = getUrl();
+		if (applicationContext == null || url == null) {
+			return null;
+		}
+		Resource resource = applicationContext.getResource(url);
 		if (resource == null || !resource.exists()) {
 			return null;
 		}
@@ -115,7 +125,7 @@ private Reader getReader(Resource resource) throws IOException {
 		return new InputStreamReader(resource.getInputStream());
 	}
 
-	private Optional<Charset> getCharset(MediaType mediaType) {
+	private Optional<Charset> getCharset(@Nullable MediaType mediaType) {
 		return Optional.ofNullable((mediaType != null) ? mediaType.getCharset() : null);
 	}
 

module/spring-boot-mustache/src/main/java/org/springframework/boot/mustache/reactive/view/MustacheViewResolver.java

@@ -18,6 +18,7 @@
 
 import com.samskivert.mustache.Mustache;
 import com.samskivert.mustache.Mustache.Compiler;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.web.reactive.result.view.AbstractUrlBasedView;
 import org.springframework.web.reactive.result.view.UrlBasedViewResolver;
@@ -34,7 +35,7 @@ public class MustacheViewResolver extends UrlBasedViewResolver {
 
 	private final Compiler compiler;
 
-	private String charset;
+	private @Nullable String charset;
 
 	/**
 	 * Create a {@code MustacheViewResolver} backed by a default instance of a

module/spring-boot-mustache/src/main/java/org/springframework/boot/mustache/reactive/view/package-info.java

@@ -18,4 +18,7 @@
  * Additional {@link org.springframework.web.reactive.result.view.View Views} for use with
  * WebFlux.
  */
+@NullMarked
 package org.springframework.boot.mustache.reactive.view;
+
+import org.jspecify.annotations.NullMarked;

module/spring-boot-mustache/src/main/java/org/springframework/boot/mustache/servlet/view/MustacheView.java

@@ -26,8 +26,11 @@
 import com.samskivert.mustache.Template;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
+import org.jspecify.annotations.Nullable;
 
+import org.springframework.context.ApplicationContext;
 import org.springframework.core.io.Resource;
+import org.springframework.util.Assert;
 import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.view.AbstractTemplateView;
 
@@ -41,9 +44,9 @@
  */
 public class MustacheView extends AbstractTemplateView {
 
-	private Compiler compiler;
+	private @Nullable Compiler compiler;
 
-	private String charset;
+	private @Nullable String charset;
 
 	/**
 	 * Set the Mustache compiler to be used by this view.
@@ -61,27 +64,40 @@ public void setCompiler(Compiler compiler) {
 	 * Set the charset used for reading Mustache template files.
 	 * @param charset the charset to use for reading template files
 	 */
-	public void setCharset(String charset) {
+	public void setCharset(@Nullable String charset) {
 		this.charset = charset;
 	}
 
 	@Override
 	public boolean checkResource(Locale locale) throws Exception {
-		Resource resource = getApplicationContext().getResource(getUrl());
-		return (resource != null && resource.exists());
+		Resource resource = getResource();
+		return resource != null;
 	}
 
 	@Override
 	protected void renderMergedTemplateModel(Map<String, Object> model, HttpServletRequest request,
 			HttpServletResponse response) throws Exception {
-		Template template = createTemplate(getApplicationContext().getResource(getUrl()));
+		Resource resource = getResource();
+		Assert.state(resource != null, "'resource' must not be null");
+		Template template = createTemplate(resource);
 		if (template != null) {
 			template.execute(model, response.getWriter());
 		}
 	}
 
+	private @Nullable Resource getResource() {
+		ApplicationContext applicationContext = getApplicationContext();
+		String url = getUrl();
+		if (applicationContext == null || url == null) {
+			return null;
+		}
+		Resource resource = applicationContext.getResource(url);
+		return (resource.exists()) ? resource : null;
+	}
+
 	private Template createTemplate(Resource resource) throws IOException {
 		try (Reader reader = getReader(resource)) {
+			Assert.state(this.compiler != null, "'compiler' must not be null");
 			return this.compiler.compile(reader);
 		}
 	}

module/spring-boot-mustache/src/main/java/org/springframework/boot/mustache/servlet/view/MustacheViewResolver.java

@@ -18,6 +18,7 @@
 
 import com.samskivert.mustache.Mustache;
 import com.samskivert.mustache.Mustache.Compiler;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.view.AbstractTemplateViewResolver;
@@ -33,7 +34,7 @@ public class MustacheViewResolver extends AbstractTemplateViewResolver {
 
 	private final Mustache.Compiler compiler;
 
-	private String charset;
+	private @Nullable String charset;
 
 	/**
 	 * Create a {@code MustacheViewResolver} backed by a default instance of a
@@ -63,7 +64,7 @@ protected Class<?> requiredViewClass() {
 	 * Set the charset.
 	 * @param charset the charset
 	 */
-	public void setCharset(String charset) {
+	public void setCharset(@Nullable String charset) {
 		this.charset = charset;
 	}
 

module/spring-boot-mustache/src/main/java/org/springframework/boot/mustache/servlet/view/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Additional {@link org.springframework.web.servlet.View Views} for use with Web MVC.
  */
+@NullMarked
 package org.springframework.boot.mustache.servlet.view;
+
+import org.jspecify.annotations.NullMarked;