Add String Escape Utils to Nifi Expression Language (redo)

[devin-fisher]

jira:NIFI-2460

Added functions to escape and unescape common transport formats that are supported by common-lang's StringEscapeUtils.

Since I added ten functions, I created a new section in the Documentation. I also moved URL encode and decode there too.

Don't add a lot of unit tests since I'm directly piping it through to StringEscapeUtils and they have extensive testing there. The test are most to verify that it is going to the right function.

[devin-fisher]

This a redo for PR #777

[mattyb149]

Reviewing...

[mattyb149]

I'm seeing CheckStyle errors:

[INFO] --- maven-checkstyle-plugin:2.15:check (check-style) @ nifi-expression-language ---
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java12 RegexpSinglelineJava: Line has trailing whitespace.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java13:1 LeftCurly: '{' should be on the previous line.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java15:5 FileTabCharacter: Line contains a tab character.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java17 RegexpSinglelineJava: Line has trailing whitespace.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java19:5 FileTabCharacter: Line contains a tab character.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java21 RegexpSinglelineJava: Line has trailing whitespace.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java23:5 FileTabCharacter: Line contains a tab character.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java27:5 FileTabCharacter: Line contains a tab character.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java29 RegexpSinglelineJava: Line has trailing whitespace.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java31:5 FileTabCharacter: Line contains a tab character.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java33 RegexpSinglelineJava: Line has trailing whitespace.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java35:5 FileTabCharacter: Line contains a tab character.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java37 RegexpSinglelineJava: Line has trailing whitespace.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java39:5 FileTabCharacter: Line contains a tab character.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java41 RegexpSinglelineJava: Line has trailing whitespace.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java43:5 FileTabCharacter: Line contains a tab character.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java47:5 FileTabCharacter: Line contains a tab character.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java49 RegexpSinglelineJava: Line has trailing whitespace.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java51:5 FileTabCharacter: Line contains a tab character.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java53 RegexpSinglelineJava: Line has trailing whitespace.
[WARNING] src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/CharSequenceTranslatorEvaluator.java54 RegexpSinglelineJava: Line has trailing whitespace.

Can you format this file? You can check to see if there are errors by going to the nifi-commons/nifi-expression-language module and running "mvn clean install -Pcontrib-check".

[devin-fisher]

Ok, fixed those errors and it now passes the contrib-check.

[joewitt]

@devin-fisher awesome how responsive you have been on this! Makes review/commit process much easier! Thank you

[mattyb149]

+1 Great job! I built, ran, and tested the functions with escaped/unescaped inputs and empty strings, everything works well. Thanks again for the contribution! Will merge to master.