import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;

@Component
public class ExampleGreeter implements Greeter {

    @PostConstruct
    public void post() {
        System.out.println("Constructed!!");
    }

    @Override
    public void hello() {
        System.out.println("Hello Gemini Blueprint World!");;
    }
}

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
           xmlns:beans="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:context="http://www.springframework.org/schema/context"
           xsi:schemaLocation="
    http://www.osgi.org/xmlns/blueprint/v1.0.0 http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <context:component-scan base-package="de.datenkollektiv.sandbox.spring.data.jdbc.example" />

    <service ref="exampleGreeter" interface="de.datenkollektiv.sandbox.spring.data.jdbc.example.Greeter" />
</blueprint>

[2019-06-21 08:06:32.682] INFO  region-dm-1                  System.out                                                        Constructed!!

  "Registered Services"
    {de.datenkollektiv.sandbox.spring.data.jdbc.example.Greeter}={org.eclipse.gemini.blueprint.bean.name=exampleGreeter, org.springframework.osgi.bean.name=exampleGreeter, osgi.service.blueprint.compname=exampleGreeter, ...

package test.postconstruct;

import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;

@Component
public class PostConstructUser
{   
    private Integer i = null;
    
    @PostConstruct
    public void init()
    {
        System.out.println( "PostConstructUser initializing: " + this );
        i = new Integer(1);
    }

    public Integer getI()
    {
        return i;
    }

}

package test.postconstruct;

import javax.inject.Inject;

public class PostConstructTester
{

    private PostConstructUser user;
    
    public void init()
    {
        if (user.getI() == null)
        {
            System.out.println("PostConstruct check failed.  Karaf is not properly handling annotated classes.");
        }
    }

    @Inject
    public void setUser( PostConstructUser user )
    {
        this.user = user;
    }
}

<?xml version="1.0" encoding="UTF-8"?>

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
           xmlns:beans="http://www.springframework.org/schema/beans"
           xmlns:context="http://www.springframework.org/schema/context"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="
            http://www.osgi.org/xmlns/blueprint/v1.0.0 http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
            http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"
           default-activation="eager">
        
    <!--
        Enables annotation configurations (e.g. @PreDestroy,
        @PostConstruct, @Autowired)
    -->
    <context:component-scan base-package="test.postconstruct"/>
       <context:property-placeholder />

    <!--<bean id="user" class="test.test.postconstruct.PostConstructUser"/>-->
  
    <bean id="tester" class="test.postconstruct.PostConstructTester"
  	    init-method="init">
  	</bean>

</blueprint>

<?xml version="1.0" encoding="UTF-8"?>
<features name="my-features">
<feature name="libs" version="1.0.0">
    <bundle start-level="32">mvn:org.apache.servicemix.bundles/org.apache.servicemix.bundles.javax-inject/1_3</bundle>
</feature>

<feature name="gemini-blueprint" description="Eclipse Gemini Blueprint support" version="3.0.0.M01">
    <feature version="1.0.0">libs</feature>
    <feature version="5.0.12.RELEASE_1">spring</feature>
    <bundle start-level="30">mvn:org.eclipse.gemini.blueprint/gemini-blueprint-core/3.0.0.M01</bundle>
    <bundle start-level="30">mvn:org.eclipse.gemini.blueprint/gemini-blueprint-io/3.0.0.M01</bundle>
    <bundle start-level="30">mvn:org.eclipse.gemini.blueprint/gemini-blueprint-extensions/3.0.0.M01</bundle>
    <bundle start-level="30">mvn:org.eclipse.gemini.blueprint/gemini-blueprint-extender/3.0.0.M01</bundle>
    <!-- Shouldn't need this, but Gemini Blueprint doesn't include Provide-Capability header for osgi.extender=osgi.blueprint
     so the deployer feature doesn't install this bundle -->
    <!--<bundle start-level="24">mvn:org.apache.karaf.deployer/org.apache.karaf.deployer.blueprint/4.2.5</bundle>-->
</feature>

<feature name="my-test-postconstruct" version="1.0.0">
    <feature version="3.0.0.M01">gemini-blueprint</feature>
    <bundle start-level="50">mvn:testing/postconstruct/3.8.0-SNAPSHOT</bundle>
</feature>

</features>

karaf@root(feature)> install libs
karaf@root(feature)> install gemini-blueprint
karaf@root(feature)> install my-test-postconstruct
karaf@root(feature)> PostConstruct check failed.  Karaf is not properly handling annotated classes.