Resolve property-dependent parameter names for exception messages

Prior to this commit when a required parameter defined as a property or
expression placeholder was missing, the exception thrown would refer to
the placeholder instead of the resolved name.

This change covers messaging handlers and web controllers, both blocking
and reactive. It also fixes the error message when handling null values
for non-required parameters, as well as in cases that need conversion.

See gh-32323
Closes gh-32462

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/RequestHeaderMethodArgumentResolverTests.java

@@ -36,6 +36,7 @@ import org.springframework.util.ReflectionUtils;
 import org.springframework.web.bind.annotation.RequestHeader;
 import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;
 import org.springframework.web.reactive.BindingContext;
+import org.springframework.web.server.MissingRequestValueException;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.ServerWebInputException;
 import org.springframework.web.testfixture.http.server.reactive.MockServerHttpRequest;
@@ -43,6 +44,7 @@ import org.springframework.web.testfixture.server.MockServerWebExchange;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 /**
  * Tests for {@link RequestHeaderMethodArgumentResolver}.
@@ -64,6 +66,7 @@ class RequestHeaderMethodArgumentResolverTests {
 	private MethodParameter paramDate;
 	private MethodParameter paramInstant;
 	private MethodParameter paramMono;
+	private MethodParameter primitivePlaceholderParam;
 
 
 	@BeforeEach
@@ -87,6 +90,7 @@ class RequestHeaderMethodArgumentResolverTests {
 		this.paramDate = new SynthesizingMethodParameter(method, 6);
 		this.paramInstant = new SynthesizingMethodParameter(method, 7);
 		this.paramMono = new SynthesizingMethodParameter(method, 8);
+		this.primitivePlaceholderParam = new SynthesizingMethodParameter(method, 9);
 	}
 
 
@@ -200,6 +204,46 @@ class RequestHeaderMethodArgumentResolverTests {
 		}
 	}
 
+	@Test
+	void missingParameterFromSystemPropertyThroughPlaceholder() {
+		String expected = "sysbar";
+		MockServerHttpRequest request = MockServerHttpRequest.get("/").build();
+		ServerWebExchange exchange = MockServerWebExchange.from(request);
+
+		System.setProperty("systemProperty", expected);
+		try {
+			Mono<Object> mono = this.resolver.resolveArgument(
+					this.paramResolvedNameWithExpression, this.bindingContext, exchange);
+
+			assertThatThrownBy(() -> mono.block())
+					.isInstanceOf(MissingRequestValueException.class)
+					.extracting("name").isEqualTo(expected);
+		}
+		finally {
+			System.clearProperty("systemProperty");
+		}
+	}
+
+	@Test
+	void notNullablePrimitiveParameterFromSystemPropertyThroughPlaceholder() {
+		String expected = "sysbar";
+		MockServerHttpRequest request = MockServerHttpRequest.get("/").build();
+		ServerWebExchange exchange = MockServerWebExchange.from(request);
+
+		System.setProperty("systemProperty", expected);
+		try {
+			Mono<Object> mono = this.resolver.resolveArgument(
+					this.primitivePlaceholderParam, this.bindingContext, exchange);
+
+			assertThatThrownBy(() -> mono.block())
+					.isInstanceOf(IllegalStateException.class)
+					.hasMessageContaining(expected);
+		}
+		finally {
+			System.clearProperty("systemProperty");
+		}
+	}
+
 	@Test
 	void notFound() {
 		Mono<Object> mono = resolver.resolveArgument(
@@ -252,7 +296,8 @@ class RequestHeaderMethodArgumentResolverTests {
 			@RequestHeader("name") Map<?, ?> unsupported,
 			@RequestHeader("name") Date dateParam,
 			@RequestHeader("name") Instant instantParam,
-			@RequestHeader Mono<String> alsoNotSupported) {
+			@RequestHeader Mono<String> alsoNotSupported,
+			@RequestHeader(value = "${systemProperty}", required = false) int primitivePlaceholderParam) {
 	}
 
 }