osgi - Bean method invocations where the bean is a proxy for an Interface & the method has no arguments fail with AmbiguousMethodCallException

[paul-mcculloch]

[Originally logged as https://issues.apache.org/jira/browse/CAMEL-20436 but closed with instructions to log here]

Using OSGi Blueprint a element can be used to inject an OSGi service into Camel. Methods on the injected service can be called via "bean:someref?method=foo"

The service is injected as a proxy to the actual OSGi service,

When BeanInfo attempts to resolve the method it sees two methods named 'foo' : The abstract method of the interface, and the concrete method of the proxy.

In camel 3.16 & earlier BeanInfo.findMostSpecificOverride() would determine that one method overrode the other, and would return the proxy's method.

From 3.17 onwards a changes was made to look at the method's declaring class' isSynthetic() value, and to not consider a synthetic class' method as overriding the interface. The blueprint proxy is synthetic so is affected.

The changes was made for https://issues.apache.org/jira/browse/CAMEL-17844 (apache/camel@5d956d2)

This can be worked around by changing the method to take at least one argument. This triggers a different path through the code - attempting to match the exchange body to the parameter. In this path the isSynthetic() flag isn't considered.