Merge pull request #163 from remondis-it/fix-mappingex-npe

Fixing NPE in building mapping exception detail text.

pom.xml

@@ -5,7 +5,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.remondis</groupId>
     <artifactId>remap</artifactId>
-    <version>4.3.6</version>
+    <version>4.3.7</version>
     <packaging>jar</packaging>
     <name>ReMap</name>
     <description>A declarative mapping library for converting objects field by field.</description>

src/main/java/com/remondis/remap/GenericParameterContext.java

@@ -53,7 +53,7 @@ private void init() {
     }
   }
 
-  private boolean isEmpty() {
+  boolean isEmpty() {
     return stack.isEmpty();
   }
 

src/main/java/com/remondis/remap/MappingException.java

@@ -151,6 +151,14 @@ static MappingException incompatibleCollectionMapping(PropertyDescriptor sourceP
     GenericParameterContext rootSrcCtx = new GenericParameterContext(sourceProperty.getReadMethod());
     GenericParameterContext rootDestCtx = new GenericParameterContext(destinationProperty.getReadMethod());
     StringBuilder builder = new StringBuilder("Incompatible nested collections found mapping\n\t");
+    String rootSourceGenericCtx = rootSrcCtx.isEmpty() ? "unknown" : rootSrcCtx.get()
+        .toString();
+    String rootDestGenericCtx = rootDestCtx.isEmpty() ? "unknown" : rootDestCtx.get()
+        .toString();
+    String sourceGenericCtx = sourceCtx.isEmpty() ? "unknown" : sourceCtx.get()
+        .toString();
+    String destGenericCtx = destCtx.isEmpty() ? "unknown" : destCtx.get()
+        .toString();
     builder.append(asString(sourceProperty))
         .append(" to ~>\n\t")
         .append(asString(destinationProperty))
@@ -165,18 +173,14 @@ static MappingException incompatibleCollectionMapping(PropertyDescriptor sourceP
         .append("\nType nesting is\n\t")
         .append("-> in source type: ")
         .append("\n\t")
-        .append(rootSrcCtx.get()
-            .toString())
+        .append(rootSourceGenericCtx)
         .append("\n\t-> in destination type: ")
         .append("\n\t")
-        .append(rootDestCtx.get()
-            .toString())
+        .append(rootDestGenericCtx)
         .append("\n\tcannot map \n\t")
-        .append(sourceCtx.get()
-            .toString())
+        .append(sourceGenericCtx)
         .append("\n\tto\n\t")
-        .append(destCtx.get()
-            .toString());
+        .append(destGenericCtx);
     return new MappingException(builder.toString());
   }