actually real fix for #2155 is here

Author: cowtowncoder

src/main/java/com/fasterxml/jackson/databind/type/TypeFactory.java

@@ -454,6 +454,7 @@ private String _resolveTypePlaceholders(JavaType sourceType, JavaType actualType
         for (int i = 0, len = expectedTypes.size(); i < len; ++i) {
             JavaType exp = expectedTypes.get(i);
             JavaType act = actualTypes.get(i);
+
             if (!_verifyAndResolvePlaceholders(exp, act)) {
                 // 14-May-2018, tatu: As per [databind#2034] it seems we better relax assignment
                 //   rules further -- at least likely "raw" (untyped, non-generic) base should probably
@@ -470,6 +471,13 @@ private String _resolveTypePlaceholders(JavaType sourceType, JavaType actualType
                         continue;
                     }
                 }
+                // 19-Nov-2018, tatu: To solve [databind#2155], let's allow type-compatible
+                //   assignment for interfaces at least...
+                if (exp.isInterface()) {
+                    if (exp.isTypeOrSuperTypeOf(act.getRawClass())) {
+                        continue;
+                    }
+                }
                 return String.format("Type parameter #%d/%d differs; can not specialize %s with %s",
                         (i+1), len, exp.toCanonical(), act.toCanonical());
             }