Fix Apache license fetching. (#512)

My fix in #484 changed the way the Apache license was handled, and all
whitespace was stripped from this popular license. Essentially, the
original code fetched it directly with the URL class while the other
licenses were fetched with Jsoup.

This commit restores this behavior. This has the unfortunate side-effect
of re-introducing boilerplate code, but it's the most cost-effective
solution for now.

Author: allisonbm92

buildSrc/src/main/groovy/com/google/firebase/gradle/plugins/license/RemoteLicenseFetcher.groovy

@@ -21,7 +21,7 @@ import org.jsoup.nodes.Document
 
 /**
  * Parse licenses from remote urls*/
-class RemoteLicenseFetcher implements Serializable {
+abstract class RemoteLicenseFetcher implements Serializable {
   private static final HtmlToPlainText TEXT_FORMATTER = new HtmlToPlainText()
 
   private final String remoteUrl
@@ -51,7 +51,7 @@ class RemoteLicenseFetcher implements Serializable {
           Thread.sleep(i * 1000)
         }
 
-        return processDocument(Jsoup.connect(remoteUrl).get())
+        return getTextAttempt()
       } catch (IOException ex) {
         if (storedEx == null) {
           storedEx = ex
@@ -64,10 +64,8 @@ class RemoteLicenseFetcher implements Serializable {
     throw storedEx
   }
 
-  /** Extracts the license text from the rest of the document. */
-  String processDocument(Document doc) {
-    return TEXT_FORMATTER.getPlainText(doc)
-  }
+  /** Attempts to download and extract the license exactly once. */
+  abstract String getTextAttempt()
 
   static final class AndroidSdkTermsFetcher extends RemoteLicenseFetcher {
 
@@ -76,10 +74,11 @@ class RemoteLicenseFetcher implements Serializable {
     }
 
     @Override
-    String processDocument(Document doc) {
+    String getTextAttempt() {
       // TODO(vkryachko, allisonbm92): Fix this silent failure.
       // This evaluates to an empty string. The HTML for this page must have changed since this
       // filter was original written. Interestingly, this is a hard-failure if run from Java.
+      def doc = Jsoup.connect(getRemoteUrl()).get()
       return TEXT_FORMATTER.getPlainText(doc.select("#body-content > div.jd-descr > div")[0])
     }
   }
@@ -89,6 +88,11 @@ class RemoteLicenseFetcher implements Serializable {
     Apache2LicenseFetcher() {
       super("http://www.apache.org/licenses/LICENSE-2.0.txt")
     }
+
+    @Override
+    String getTextAttempt() {
+      return getRemoteUrl().toURL().getText()
+    }
   }
 
   static final class AnotherApache2LicenseFetcher extends RemoteLicenseFetcher {
@@ -98,7 +102,8 @@ class RemoteLicenseFetcher implements Serializable {
     }
 
     @Override
-    String processDocument(Document doc) {
+    String getTextAttempt() {
+      def doc = Jsoup.connect(getRemoteUrl()).get()
       return TEXT_FORMATTER.getPlainText(doc.select("#content-wrapper").get(0))
     }
   }
@@ -108,6 +113,11 @@ class RemoteLicenseFetcher implements Serializable {
     YetAnotherApache2LicenseFetcher() {
       super("http://www.apache.org/licenses/LICENSE-2.0")
     }
+
+    @Override
+    String getTextAttempt() {
+      return getRemoteUrl().toURL().getText()
+    }
   }
 
   static final class BSDLicenseFetcher extends RemoteLicenseFetcher {
@@ -117,7 +127,8 @@ class RemoteLicenseFetcher implements Serializable {
     }
 
     @Override
-    String processDocument(Document doc) {
+    String getTextAttempt() {
+      def doc = Jsoup.connect(getRemoteUrl()).get()
       return TEXT_FORMATTER.getPlainText(doc.select("#content-wrapper").get(0))
     }
   }
@@ -129,7 +140,8 @@ class RemoteLicenseFetcher implements Serializable {
     }
 
     @Override
-    String processDocument(Document doc) {
+    String getTextAttempt() {
+      def doc = Jsoup.connect(getRemoteUrl()).get()
       return TEXT_FORMATTER.getPlainText(doc.select("#deed").get(0))
     }
   }
@@ -141,7 +153,8 @@ class RemoteLicenseFetcher implements Serializable {
     }
 
     @Override
-    String processDocument(Document doc) {
+    String getTextAttempt() {
+      def doc = Jsoup.connect(getRemoteUrl()).get()
       return TEXT_FORMATTER.getPlainText(doc.select("#content-wrapper").get(0))
     }
   }
@@ -153,7 +166,8 @@ class RemoteLicenseFetcher implements Serializable {
     }
 
     @Override
-    String processDocument(Document doc) {
+    String getTextAttempt() {
+      def doc = Jsoup.connect(getRemoteUrl()).get()
       return TEXT_FORMATTER.getPlainText(doc.select("#content-wrapper").get(0))
     }
   }
@@ -166,7 +180,8 @@ class RemoteLicenseFetcher implements Serializable {
     }
 
     @Override
-    String processDocument(Document doc) {
+    String getTextAttempt() {
+      def doc = Jsoup.connect(getRemoteUrl()).get()
       return TEXT_FORMATTER.getPlainText(doc.select("body > table > tbody > tr:nth-child(2) > td:nth-child(2) > table > tbody > tr:nth-child(3) > td > en > blockquote").get(0))
     }
   }