#2544: fix missing helper methods for ReverseConversion

processor/src/main/java/org/mapstruct/ap/internal/conversion/ReverseConversion.java

@@ -5,12 +5,12 @@
  */
 package org.mapstruct.ap.internal.conversion;
 
-import java.util.Collections;
 import java.util.List;
+
+import org.mapstruct.ap.internal.model.HelperMethod;
 import org.mapstruct.ap.internal.model.common.Assignment;
 import org.mapstruct.ap.internal.model.common.ConversionContext;
 import org.mapstruct.ap.internal.model.common.FieldReference;
-import org.mapstruct.ap.internal.model.HelperMethod;
 
 /**
  *  * A {@link ConversionProvider} which creates the inversed conversions for a
@@ -42,7 +42,7 @@ public class ReverseConversion implements ConversionProvider {
 
     @Override
     public List<HelperMethod> getRequiredHelperMethods(ConversionContext conversionContext) {
-        return Collections.emptyList();
+        return conversionProvider.getRequiredHelperMethods( conversionContext );
     }
 
     @Override

processor/src/test/java/org/mapstruct/ap/test/bugs/_2544/Issue2544Mapper.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2544;
+
+import java.math.BigDecimal;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * @author Ben Zegveld
+ */
+@Mapper
+public interface Issue2544Mapper {
+
+    Issue2544Mapper INSTANCE = Mappers.getMapper( Issue2544Mapper.class );
+
+    @Mapping( target = "bigNumber", source = ".", numberFormat = "##0.#####E0" )
+    Target map(String s);
+
+    class Target {
+
+        private BigDecimal bigNumber;
+
+        public BigDecimal getBigNumber() {
+            return bigNumber;
+        }
+
+        public void setBigNumber(BigDecimal bigNumber) {
+            this.bigNumber = bigNumber;
+        }
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_2544/Issue2544Test.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2544;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.math.BigDecimal;
+
+import org.mapstruct.ap.testutil.IssueKey;
+import org.mapstruct.ap.testutil.ProcessorTest;
+import org.mapstruct.ap.testutil.WithClasses;
+
+/**
+ * @author Ben Zegveld
+ */
+@IssueKey( "2544" )
+@WithClasses( { Issue2544Mapper.class } )
+public class Issue2544Test {
+
+    @ProcessorTest
+    public void shouldConvert() {
+        Issue2544Mapper.Target target = Issue2544Mapper.INSTANCE.map( "123.45679E6" );
+
+        assertThat( target ).isNotNull();
+        assertThat( target.getBigNumber() ).isEqualTo( new BigDecimal( "1.2345679E+8" ) );
+    }
+}