[LANG-1648] MethodUtils.getAnnotation fails with "Found multiple candidates for method ..."

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.12.0
• Component/s: lang.*
• Assignee: Unassigned
• Reporter: Michele Preti
• Created: 08/Mar/21 14:13
• Updated: 08/Mar/21 14:16

Description

I will use jackson ObjectMapper as an example, but this will happen on any class with multiple "candidates" methods (no exact matches)

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

Method method = ObjectMapper.class.getDeclaredMethod("writeTree",
    new Class<?>[] {JsonGenerator.class, JsonNode.class});
MethodUtils.getAnnotation(method, NonNull.class, true, true);

will fail with

Exception in thread "main" java.lang.IllegalStateException: Found multiple candidates for method writeTree(class com.fasterxml.jackson.core.JsonGenerator,class com.fasterxml.jackson.databind.JsonNode) on class com.fasterxml.jackson.core.ObjectCodec : [public abstract void com.fasterxml.jackson.core.ObjectCodec.writeTree(com.fasterxml.jackson.core.JsonGenerator,com.fasterxml.jackson.core.TreeNode) throws java.io.IOException,public abstract void com.fasterxml.jackson.core.TreeCodec.writeTree(com.fasterxml.jackson.core.JsonGenerator,com.fasterxml.jackson.core.TreeNode) throws java.io.IOException,com.fasterxml.jackson.core.JsonProcessingException]Exception in thread "main" java.lang.IllegalStateException: Found multiple candidates for method writeTree(class com.fasterxml.jackson.core.JsonGenerator,class com.fasterxml.jackson.databind.JsonNode) on class com.fasterxml.jackson.core.ObjectCodec : [public abstract void com.fasterxml.jackson.core.ObjectCodec.writeTree(com.fasterxml.jackson.core.JsonGenerator,com.fasterxml.jackson.core.TreeNode) throws java.io.IOException,public abstract void com.fasterxml.jackson.core.TreeCodec.writeTree(com.fasterxml.jackson.core.JsonGenerator,com.fasterxml.jackson.core.TreeNode) throws java.io.IOException,com.fasterxml.jackson.core.JsonProcessingException] 
    at org.apache.commons.lang3.reflect.MethodUtils.getMatchingMethod(MethodUtils.java:784) 
    at org.apache.commons.lang3.reflect.MethodUtils.getAnnotation(MethodUtils.java:988)
    ...

The problem is that getAnnotation() is using getMatchingMethod() to search for any overriden method in the superclasses

getMatchingMethod() will not return overriden methods in superclass, but any similar method: same name and with isAssignable() parameters.

getMatchingMethod() in itself is correct, even if a getMatchingMethod*s*() that could return multiple matchng methods might be usefull
but getAnnotation() should not use it, instead it should simply use

acls.getDeclaredMethod(method.getName(), method.getParameterTypes())

or getMethod()
because it is only interested in overridden methods (same name and exactly same parameters)