solving problem of compilation on ProviderContext's class
using get or default in Map to get the code more cleaner
removing manual add all
update the code using lambda
removing manual add all
removing unnused imports
Merge pull request #20 from otaviojava/provider_problem

solving problem of compilation on ProviderContext's class
Merge pull request #21 from otaviojava/abstractcontext_get_default

using get or default in Map to get the code more cleaner
Merge pull request #22 from otaviojava/manual_add_all

removing manual add all
Merge pull request #23 from otaviojava/lamdba

Using lambda resources
treating null with Optional or Objects.isNull
treating not null with Objects.notNull
Merge pull request #24 from otaviojava/null_util

treating not null and null with new resources of Java 8.
Fixed issue: preventing unnecessary creation of map instances.
Fixed severe issues:
- invalid keys used for context store of values.
- Fixed broken equals on AbstractContext
efficient and clean way to do hash code with Java 8
Merge pull request #25 from otaviojava/hash_code

efficient and clean way to do hash code with Java 8
efficient and clean way to do equals with Java 8
efficient and clean way to do equals with Java 8
Merge pull request #26 from otaviojava/hash_code

efficient and clean way to do equals with Java 8
fix compare to