Further adaption of new config class

src/main/java/ca/uhn/fhir/jpa/starter/FhirServerConfigR4.java

@@ -4,6 +4,7 @@ import ca.uhn.fhir.context.ConfigurationException;
 import ca.uhn.fhir.jpa.config.BaseJavaConfigR4;
 import ca.uhn.fhir.jpa.search.DatabaseBackedPagingProvider;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Primary;
@@ -16,6 +17,7 @@ import javax.sql.DataSource;
 
 @Configuration
 @Profile("r4")
+@ConditionalOnClass(DataSource.class)
 public class FhirServerConfigR4 extends BaseJavaConfigR4 {
 
     @Autowired