Refine BindingReflectionHintsRegistrar

This commit refines BindingReflectionHintsRegistrar to handle
correctly a use case with multiple levels of nested generics.

Closes gh-28683

Author: sdeleuze

spring-core/src/main/java/org/springframework/aot/hint/support/BindingReflectionHintsRegistrar.java

@@ -142,7 +142,6 @@ private void collectReferencedTypes(Set<Type> seen, Set<Class<?>> types, @Nullab
 		if (type == null || seen.contains(type)) {
 			return;
 		}
-		seen.add(type);
 		ResolvableType resolvableType = ResolvableType.forType(type);
 		Class<?> clazz = resolvableType.resolve();
 		if (clazz != null) {

spring-core/src/test/java/org/springframework/aot/hint/support/BindingReflectionHintsRegistrarTests.java

@@ -18,6 +18,7 @@
 
 import java.lang.reflect.Type;
 import java.util.List;
+import java.util.Set;
 
 import org.junit.jupiter.api.Test;
 
@@ -184,6 +185,17 @@ void registerTypeForSerializationWithResolvableType() {
 				});
 	}
 
+	@Test
+	void registerTypeForSerializationWithMultipleLevelsAndCollection() {
+		bindingRegistrar.registerReflectionHints(this.hints.reflection(), SampleClassA.class);
+		assertThat(this.hints.reflection().typeHints()).satisfiesExactlyInAnyOrder(
+				typeHint -> assertThat(typeHint.getType()).isEqualTo(TypeReference.of(SampleClassA.class)),
+				typeHint -> assertThat(typeHint.getType()).isEqualTo(TypeReference.of(SampleClassB.class)),
+				typeHint -> assertThat(typeHint.getType()).isEqualTo(TypeReference.of(SampleClassC.class)),
+				typeHint -> assertThat(typeHint.getType()).isEqualTo(TypeReference.of(String.class)),
+				typeHint -> assertThat(typeHint.getType()).isEqualTo(TypeReference.of(Set.class)));
+	}
+
 
 	static class SampleEmptyClass {
 	}
@@ -244,4 +256,22 @@ public ResolvableType getResolvableType() {
 		}
 	}
 
+	static class SampleClassA {
+		public Set<SampleClassB> getB() {
+			return null;
+		}
+	}
+
+	static class SampleClassB {
+		public SampleClassC getC() {
+			return null;
+		}
+	}
+
+	class SampleClassC {
+		public String getString() {
+			return "";
+		}
+	}
+
 }