Support for ResolvableType.getType().getTypeName() on Java 8

Issue: SPR-16535

spring-core/src/main/java/org/springframework/core/ResolvableType.java

@@ -1495,6 +1495,22 @@ public class ResolvableType implements Serializable {
 			this.typeArguments = typeArguments;
 		}
 
+		@Override
+		public String getTypeName() {
+			StringBuilder result = new StringBuilder(this.rawType.getTypeName());
+			if (this.typeArguments.length > 0) {
+				result.append('<');
+				for (int i = 0; i < this.typeArguments.length; i++) {
+					if (i > 0) {
+						result.append(", ");
+					}
+					result.append(this.typeArguments[i].getTypeName());
+				}
+				result.append('>');
+			}
+			return result.toString();
+		}
+
 		@Override
 		@Nullable
 		public Type getOwnerType() {
@@ -1528,6 +1544,11 @@ public class ResolvableType implements Serializable {
 		public int hashCode() {
 			return (this.rawType.hashCode() * 31 + Arrays.hashCode(this.typeArguments));
 		}
+
+		@Override
+		public String toString() {
+			return getTypeName();
+		}
 	}