Fix null parameter in conversion error message.

src/main/java/org/prebid/server/auction/ExchangeService.java

@@ -903,9 +903,7 @@ price, currencyRates(bidRequest), adServerCurrency,
                 }
                 updatedBidderBids.add(bidderBid);
             } catch (PreBidException e) {
-                errors.add(BidderError.generic(
-                        String.format("Unable to covert bid currency %s to desired ad server currency %s. %s",
-                                bidCurrency, adServerCurrency, e.getMessage())));
+                errors.add(BidderError.generic(e.getMessage()));
             }
         }
 

src/main/java/org/prebid/server/currency/CurrencyConversionService.java

@@ -172,7 +172,9 @@ public BigDecimal convertCurrency(BigDecimal price, Map<String, Map<String, BigD
                 adServerCurrency, effectiveBidCurrency);
 
         if (conversionRate == null) {
-            throw new PreBidException("no currency conversion available");
+            throw new PreBidException(
+                    String.format("Unable to convert bid currency %s to desired ad server currency %s",
+                            effectiveBidCurrency, adServerCurrency));
         }
 
         return price.divide(conversionRate, DEFAULT_PRICE_PRECISION, RoundingMode.HALF_EVEN);

src/test/java/org/prebid/server/auction/CurrencyConversionServiceTest.java

@@ -231,15 +231,15 @@ public void convertCurrencyShouldFailWhenRequestRatesIsNullAndNoExternalRatesPro
         assertThatExceptionOfType(PreBidException.class)
                 .isThrownBy(() -> currencyConversionService.convertCurrency(BigDecimal.ONE, null, EUR, GBP,
                         false))
-                .withMessage("no currency conversion available");
+                .withMessage("Unable to convert bid currency GBP to desired ad server currency EUR");
     }
 
     @Test
     public void convertCurrencyShouldThrowPrebidExceptionIfServerAndRequestRatesAreNull() {
         // when and then
         assertThatExceptionOfType(PreBidException.class)
                 .isThrownBy(() -> currencyService.convertCurrency(BigDecimal.ONE, null, USD, EUR, false))
-                .withMessage("no currency conversion available");
+                .withMessage("Unable to convert bid currency EUR to desired ad server currency USD");
     }
 
     @Test
@@ -257,7 +257,7 @@ public void convertCurrencyShouldThrowPrebidExceptionIfMultiplierWasNotFoundFrom
         assertThatExceptionOfType(PreBidException.class)
                 .isThrownBy(() -> currencyService.convertCurrency(BigDecimal.ONE, requestConversionRates, EUR, AUD,
                         false))
-                .withMessage("no currency conversion available");
+                .withMessage("Unable to convert bid currency AUD to desired ad server currency EUR");
     }
 
     @Test
@@ -271,7 +271,7 @@ public void convertCurrencyShouldThrowExceptionWhenCurrencyServerResponseStatusN
         // then
         assertThatExceptionOfType(PreBidException.class)
                 .isThrownBy(() -> currencyService.convertCurrency(BigDecimal.ONE, null, UAH, AUD, false))
-                .withMessage("no currency conversion available");
+                .withMessage("Unable to convert bid currency AUD to desired ad server currency UAH");
     }
 
     @Test
@@ -285,7 +285,7 @@ public void convertCurrencyShouldThrowExceptionWhenCurrencyServerResponseContain
         // then
         assertThatExceptionOfType(PreBidException.class)
                 .isThrownBy(() -> currencyService.convertCurrency(BigDecimal.ONE, null, UAH, AUD, false))
-                .withMessage("no currency conversion available");
+                .withMessage("Unable to convert bid currency AUD to desired ad server currency UAH");
     }
 
     @SuppressWarnings("unchecked")

src/test/java/org/prebid/server/auction/ExchangeServiceTest.java

@@ -1879,7 +1879,7 @@ public void shouldDropBidIfPrebidExceptionWasThrownDuringCurrencyConversion() {
                 identity());
 
         given(currencyService.convertCurrency(any(), any(), any(), any(), any()))
-                .willThrow(new PreBidException("no currency conversion available"));
+                .willThrow(new PreBidException("Unable to convert bid currency CUR to desired ad server currency USD"));
 
         // when
         exchangeService.holdAuction(givenRequestContext(bidRequest)).result();
@@ -1890,8 +1890,8 @@ public void shouldDropBidIfPrebidExceptionWasThrownDuringCurrencyConversion() {
 
         assertThat(argumentCaptor.getValue()).hasSize(1);
 
-        final BidderError expectedError = BidderError.generic("Unable to covert bid currency CUR to desired ad"
-                + " server currency USD. no currency conversion available");
+        final BidderError expectedError =
+                BidderError.generic("Unable to convert bid currency CUR to desired ad server currency USD");
         final BidderSeatBid firstSeatBid = argumentCaptor.getValue().get(0).getSeatBid();
         assertThat(firstSeatBid.getBids()).isEmpty();
         assertThat(firstSeatBid.getErrors()).containsOnly(expectedError);
@@ -1948,7 +1948,8 @@ public void shouldUpdatePriceForOneBidAndDropAnotherIfPrebidExceptionHappensForS
 
         final BigDecimal updatedPrice = BigDecimal.valueOf(10.0);
         given(currencyService.convertCurrency(any(), any(), any(), any(), any())).willReturn(updatedPrice)
-                .willThrow(new PreBidException("no currency conversion available"));
+                .willThrow(
+                        new PreBidException("Unable to convert bid currency CUR2 to desired ad server currency USD"));
 
         // when
         exchangeService.holdAuction(givenRequestContext(bidRequest)).result();
@@ -1963,8 +1964,8 @@ public void shouldUpdatePriceForOneBidAndDropAnotherIfPrebidExceptionHappensForS
 
         final Bid expectedBid = Bid.builder().price(updatedPrice).build();
         final BidderBid expectedBidderBid = BidderBid.of(expectedBid, banner, "CUR1");
-        final BidderError expectedError = BidderError.generic("Unable to covert bid currency CUR2 to desired ad"
-                + " server currency USD. no currency conversion available");
+        final BidderError expectedError =
+                BidderError.generic("Unable to convert bid currency CUR2 to desired ad server currency USD");
 
         final BidderSeatBid firstSeatBid = argumentCaptor.getValue().get(0).getSeatBid();
         assertThat(firstSeatBid.getBids()).containsOnly(expectedBidderBid);
@@ -1989,7 +1990,7 @@ public void shouldRespondWithOneBidAndErrorWhenBidResponseContainsOneUnsupported
         final BigDecimal updatedPrice = BigDecimal.valueOf(20);
         given(currencyService.convertCurrency(any(), any(), any(), any(), any())).willReturn(updatedPrice);
         given(currencyService.convertCurrency(any(), any(), eq("BAD"), eq("CUR"), any()))
-                .willThrow(new PreBidException("no currency conversion available"));
+                .willThrow(new PreBidException("Unable to convert bid currency CUR to desired ad server currency BAD"));
 
         // when
         exchangeService.holdAuction(givenRequestContext(bidRequest)).result();
@@ -2009,8 +2010,8 @@ public void shouldRespondWithOneBidAndErrorWhenBidResponseContainsOneUnsupported
                 .flatExtracting(BidderSeatBid::getBids)
                 .containsOnly(expectedBidderBid);
 
-        final BidderError expectedError = BidderError.generic("Unable to covert bid currency CUR to desired ad"
-                + " server currency BAD. no currency conversion available");
+        final BidderError expectedError =
+                BidderError.generic("Unable to convert bid currency CUR to desired ad server currency BAD");
         assertThat(argumentCaptor.getValue())
                 .extracting(BidderResponse::getSeatBid)
                 .flatExtracting(BidderSeatBid::getErrors)