Kobler: Fix NPE (#3885)

Author: CTMBNara

src/main/java/org/prebid/server/bidder/kobler/KoblerBidder.java

@@ -10,6 +10,7 @@
 import com.iab.openrtb.response.BidResponse;
 import com.iab.openrtb.response.SeatBid;
 import org.apache.commons.collections4.CollectionUtils;
+import org.apache.commons.lang3.BooleanUtils;
 import org.prebid.server.bidder.Bidder;
 import org.prebid.server.bidder.model.BidderBid;
 import org.prebid.server.bidder.model.BidderCall;
@@ -126,7 +127,7 @@ private List<String> normalizeCurrencies(BidRequest bidRequest) {
 
     private boolean isTest(Imp imp, List<BidderError> errors) {
         try {
-            return parseImpExt(imp).getTest();
+            return BooleanUtils.isTrue(parseImpExt(imp).getTest());
         } catch (PreBidException e) {
             errors.add(BidderError.badInput(e.getMessage()));
             return false;

src/test/java/org/prebid/server/bidder/kobler/KoblerBidderTest.java

@@ -133,6 +133,21 @@ public void makeHttpRequestsShouldUseDefaultEndpointWhenTestModeDisabled() {
                 .containsExactly(ENDPOINT_URL);
     }
 
+    @Test
+    public void makeHttpRequestsShouldUseDefaultEndpointWhenTestModeAbsent() {
+        // given
+        final BidRequest bidRequest = givenBidRequest(givenImp(
+                imp -> imp.ext(mapper.valueToTree(ExtPrebid.of(null, ExtImpKobler.of(null))))));
+
+        // when
+        final Result<List<HttpRequest<BidRequest>>> result = target.makeHttpRequests(bidRequest);
+
+        // then
+        assertThat(result.getValue())
+                .extracting(HttpRequest::getUri)
+                .containsExactly(ENDPOINT_URL);
+    }
+
     @Test
     public void makeHttpRequestsShouldAddUsdToCurrenciesIfMissing() {
         // given