`JsonNode.binaryValue()` ignores illegal character if it's the last one

[binoternary]

Some invalid base64 inputs do not throw an exception while others do.

Code to reproduce the problem (using Jackson version 2.8.4):

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Base64;

public class JacksonBase64Decode {
    public static void main(String[] args) {
        ObjectMapper mapper = new ObjectMapper();

        String base64Hello = Base64.getEncoder().encodeToString("hello".getBytes(StandardCharsets.US_ASCII));
        String json_1 = "{\"foo\": \""+ base64Hello +"\"}";
        String json_2 = "{\"foo\": \""+ base64Hello + "!" +"\"}";
        String json_3 = "{\"foo\": \""+ base64Hello + "!!" +"\"}";

        for (String json : Arrays.asList(json_1, json_2, json_3)) {
            try {
                JsonNode tree = mapper.readTree(json);
                JsonNode foo = tree.get("foo");
                byte[] value = foo.binaryValue();
                String reEncodedValue = Base64.getEncoder().encodeToString(value);
                System.out.printf("original json: %s; original textValue: %s; re-encoded binary value: %s%n",
                        json, foo.textValue(), reEncodedValue);
            } catch (Exception e) {
                System.out.printf("original json: %s; exception: %s%n", json, e.getMessage());
            }
        }
    }
}

Output:

original json: {"foo": "aGVsbG8="}; original textValue: aGVsbG8=; re-encoded binary value: aGVsbG8=
original json: {"foo": "aGVsbG8=!"}; original textValue: aGVsbG8=!; re-encoded binary value: aGVsbG8=
original json: {"foo": "aGVsbG8=!!"}; exception: Illegal character '!' (code 0x21) in base64 content
 at [Source: N/A; line: -1, column: -1]

First case - everything OK
Second case - I would expect the same behavior as in the third case
Third case - intuitively it's not surprising that an exception is thrown here.

However there seems to be a mismatch between code behavior and JavaDoc of binaryValue() method which says that JsonNode::binaryValue returns "Binary data this node contains, iff it is a binary node; null otherwise". So based on the javadoc I would expect that in the second and third case binaryValue() returns null.

[cowtowncoder]

Interesting. If I use direct data-binding with property of type byte[], tests work as expected.
So it seems to be due to slightly different code path for tree access that is at work here...