JAR file detection

Previously, the detection algorithms for Ratpack and Spring Boot
contained a bug.  This bug manifested itself as detection a JAR that
_almost_ matched the name required for discrimination, but when
extracting the version, everything would crash.  This bug was hidden
during testing because the ordering that files were listed affected
whether the bug manifested.  This change updates the detection
algorithms so that the ordering of the files no longer matters.

Author: nebhale

lib/java_buildpack/util/ratpack_utils.rb

@@ -32,21 +32,27 @@ class << self
         # @param [Application] application the application to search
         # @return [Boolean] +true+ if the application is a Ratpack application, +false+ otherwise
         def is?(application)
-          (application.root + RATPACK_CORE_FILE_PATTERN).glob.any?
+          jar application
         end
 
         # The version of Ratpack used by the application
         #
         # @param [Application] application the application to search
         # @return [String] the version of Ratpack used by the application
         def version(application)
-          (application.root + RATPACK_CORE_FILE_PATTERN).glob.first.to_s.match(/.*ratpack-core-(.*)\.jar/)[1]
+          jar(application).to_s.match(RATPACK_CORE_FILE_PATTERN)[1]
         end
 
-        RATPACK_CORE_FILE_PATTERN = '**/lib/ratpack-core-*.jar'.freeze
+        private
+
+        RATPACK_CORE_FILE_PATTERN = /.*ratpack-core-(.*)\.jar/.freeze
 
         private_constant :RATPACK_CORE_FILE_PATTERN
 
+        def jar(application)
+          (application.root + '**/lib/*.jar').glob.find { |jar| jar.to_s =~ RATPACK_CORE_FILE_PATTERN }
+        end
+
       end
 
     end

lib/java_buildpack/util/spring_boot_utils.rb

@@ -32,21 +32,27 @@ class << self
         # @param [Application] application the application to search
         # @return [Boolean] +true+ if the application is a Spring Boot application, +false+ otherwise
         def is?(application)
-          (application.root + SPRING_BOOT_CORE_FILE_PATTERN).glob.any?
+          jar application
         end
 
         # The version of Spring Boot used by the application
         #
         # @param [Application] application the application to search
         # @return [String] the version of Spring Boot used by the application
         def version(application)
-          (application.root + SPRING_BOOT_CORE_FILE_PATTERN).glob.first.to_s.match(/.*spring-boot-([^-]*)\.jar/)[1]
+          jar(application).to_s.match(SPRING_BOOT_CORE_FILE_PATTERN)[1]
         end
 
-        SPRING_BOOT_CORE_FILE_PATTERN = '**/lib/spring-boot-*.jar'.freeze
+        private
+
+        SPRING_BOOT_CORE_FILE_PATTERN = /.*spring-boot-([^-]*)\.jar/.freeze
 
         private_constant :SPRING_BOOT_CORE_FILE_PATTERN
 
+        def jar(application)
+          (application.root + '**/lib/*.jar').glob.find { |jar| jar.to_s =~ SPRING_BOOT_CORE_FILE_PATTERN }
+        end
+
       end
 
     end