Re-add OSGI manifest

Fixes #107

Author: michel-kraemer

build.gradle

@@ -1,5 +1,6 @@
 plugins {
     id("io.github.gradle-nexus.publish-plugin") version "1.1.0"
+    id("biz.aQute.bnd.builder") version "6.2.0"
 }
 
 apply plugin: 'maven-publish'
@@ -108,6 +109,18 @@ dependencies {
     integrationTest213 jacksonDatabind + '2.13.0'
 }
 
+jar {
+    // define OSGi bundle manifest
+    bundle {
+        bnd(
+            "Bundle-Name": "bson4jackson",
+            "Bundle-SymbolicName": "de.undercouch.bson4jackson",
+            "Bundle-Vendor": "Michel Kraemer",
+            '-exportcontents': "de.undercouch.*;version=${version}"
+        )
+    }
+}
+
 task doIntegrationTest21(type: Test) {
     useJUnit {
         excludeCategories 'de.undercouch.bson4jackson.RequiresJackson_v2_3'