Ensure getters have non-void return types in SpEL

Closes gh-36800

spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectivePropertyAccessor.java

@@ -374,10 +374,11 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
 	 * Find a getter method for the specified property.
 	 */
 	protected @Nullable Method findGetterForProperty(String propertyName, Class<?> clazz, boolean mustBeStatic) {
-		Method method = findMethodForProperty(getPropertyMethodSuffixes(propertyName),
+		String[] methodSuffixes = getPropertyMethodSuffixes(propertyName);
+		Method method = findMethodForProperty(methodSuffixes,
 				"get", clazz, mustBeStatic, 0, ANY_TYPES);
 		if (method == null) {
-			method = findMethodForProperty(getPropertyMethodSuffixes(propertyName),
+			method = findMethodForProperty(methodSuffixes,
 					"is", clazz, mustBeStatic, 0, BOOLEAN_TYPES);
 			if (method == null) {
 				// Record-style plain accessor method, for example, name()
@@ -385,6 +386,9 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
 						"", clazz, mustBeStatic, 0, ANY_TYPES);
 			}
 		}
+		if (method != null && method.getReturnType() == void.class) {
+			method = null; // not a valid accessor method
+		}
 		return method;
 	}
 

spring-expression/src/test/java/org/springframework/expression/spel/PropertyAccessTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.expression.spel;
 
+import java.lang.reflect.Method;
 import java.time.ZoneId;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -39,6 +40,7 @@ import org.springframework.expression.spel.support.StandardEvaluationContext;
 import org.springframework.expression.spel.testresources.Inventor;
 import org.springframework.expression.spel.testresources.Person;
 import org.springframework.expression.spel.testresources.RecordPerson;
+import org.springframework.util.ClassUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
@@ -202,6 +204,16 @@ class PropertyAccessTests extends AbstractExpressionTests {
 		target.setName("p2");
 		assertThat(expr.getValue(context, target)).isEqualTo("p2");
 
+		assertThatSpelEvaluationException()
+				.isThrownBy(() -> parser.parseExpression("nonexistent").getValue(context, target))
+				.extracting(SpelEvaluationException::getMessageCode).isEqualTo(SpelMessage.PROPERTY_OR_FIELD_NOT_READABLE);
+
+		Method getInvalid = ClassUtils.getMethod(Person.class, "getInvalid");
+		assertThat(getInvalid.getReturnType()).isEqualTo(void.class);
+		assertThatSpelEvaluationException()
+				.isThrownBy(() -> parser.parseExpression("invalid").getValue(context, target))
+				.extracting(SpelEvaluationException::getMessageCode).isEqualTo(SpelMessage.PROPERTY_OR_FIELD_NOT_READABLE);
+
 		assertThatSpelEvaluationException()
 				.isThrownBy(() -> parser.parseExpression("name='p3'").getValue(context, target))
 				.extracting(SpelEvaluationException::getMessageCode).isEqualTo(SpelMessage.NOT_ASSIGNABLE);

spring-expression/src/test/java/org/springframework/expression/spel/testresources/Person.java

@@ -59,4 +59,8 @@ public class Person {
 		return company;
 	}
 
+	public void getInvalid() {
+		// no-op
+	}
+
 }