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

["Michele Preti (Jira)" <ji...@apache.org>]

Michele Preti created LANG-1648:
-----------------------------------

             Summary: MethodUtils.getAnnotation fails with "Found multiple candidates for method ..."
                 Key: LANG-1648
                 URL: https://issues.apache.org/jira/browse/LANG-1648
             Project: Commons Lang
          Issue Type: Bug
          Components: lang.*
    Affects Versions: 3.12.0
            Reporter: Michele Preti


I will use jackson ObjectMapper as an example, but this will happen on any class with multiple "candidates" methods (no exact matches)
{code:java}
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);
{code}
will fail with
{code:java}
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)
    ...{code}
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
{code:java}
acls.getDeclaredMethod(method.getName(), method.getParameterTypes())
{code}
or getMethod()
 because it is only interested in overridden methods (same name and exactly same parameters)



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