pin used guava version to the one used in kamon-opentelemetry

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

bom/pom.xml

@@ -66,6 +66,12 @@
 
         <!-- ### Metrics and Tracing -->
         <kamon.version>2.2.2</kamon.version>
+        <!-- When updating Kamon, please update the guava version below too to the used version in Kamon!
+             Guava is needed by kamon-opentelemetry (as traces are sent via gRPC library depending on Guava).
+             We need to explicitly "pin" it as a test dependency (docker-java-core) also pulls in Guava, but an older
+             version which somehow conflicts:
+        -->
+        <guava.version>30.0-android</guava.version>
 
         <jsr305.version>3.0.2</jsr305.version>
 
@@ -425,6 +431,11 @@
                 <artifactId>kamon-opentelemetry_${scala.version}</artifactId>
                 <version>${kamon.version}</version>
             </dependency>
+            <dependency>
+                <groupId>com.google.guava</groupId>
+                <artifactId>guava</artifactId>
+                <version>${guava.version}</version>
+            </dependency>
 
             <!-- ### Compile - own artifacts ### -->
             <dependency>