Update Endpoints Migration Sample

[frankyn]

PR to update Endpoints Migration Sample

Changes

• Updated README
  • updated legacy documentation links to new location https://cloud.google.com/endpoints/docs/frameworks/legacy/v1/java
  • called out discovery document in README
• Updated dependency/plugin versions
• Added migration sample to appengine/pom.xml

[codecov-io]

Codecov Report

Merging #661 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #661   +/-   ##
=========================================
  Coverage     55.84%   55.84%           
  Complexity      202      202           
=========================================
  Files            74       74           
  Lines          2052     2052           
  Branches        131      131           
=========================================
  Hits           1146     1146           
  Misses          874      874           
  Partials         32       32

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 853233b...7dd2a0b. Read the comment docs.

[frankyn]

Failure was related to Vision sample. Rebuilding..

[lesv]

@gguuss Can you look at the flaky vision sample? Frank ok to merge.

[gguuss]

@lesv @frankyn Vision tests are passing for me, but I'll take a closer look at the build break.

[lesv]

@gguuss Thanks for looking, but it's sounding like there is a flaky test.

[gguuss]

@lesv The test failed from local file then succeeded from GCS with the same image. Now I'm seeing (rarely) "image processing" errors from the API, e.g.:

   detectWebAnnotationsGcs(com.example.vision.DetectIT)  Time elapsed: 6.69 sec  <<< FAILURE!
    java.lang.AssertionError:
    Not true that <"Error: image-annotator::Web detection error.: Image processing error!
"> contains <"Palace">
    	at com.example.vision.DetectIT.detectWebAnnotationsGcs(DetectIT.java:249)
    Caused by: java.lang.AssertionError:
    Not true that <"Error: image-annotator::Web detection error.: Image processing error!
"> contains <"Palace">
    	at com.example.vision.DetectIT.detectWebAnnotationsGcs(DetectIT.java:249)

I'm not sure these are specific to the tests or the sample and I'm not seeing error codes in the console.

I'm occasionally seeing:

Not true that <"Error: image-annotator::error(12): We can not access the URL currently. Please download the image and pass it in.
"> contains <"Palace of Fine Arts">
	at com.example.vision.DetectIT.testLandmarksUrl(DetectIT.java:132)
Caused by: java.lang.AssertionError:
Not true that <"Error: image-annotator::error(12): We can not access the URL currently. Please download the image and pass it in.
"> contains <"Palace of Fine Arts">
	at com.example.vision.DetectIT.testLandmarksUrl(DetectIT.java:132)

As well, this does seem to happen more frequently on landmarks GCS URI... and http:// URIs. Maybe the http image hosting is throttling us?

[gguuss]

Hopefully PR 663 resolves our flaky test.