AAPT2: Fix JavaDoc first sentence extraction.

The old algorithm for detecting the first sentence of a JavaDoc comment
looked for the first occurence of '.'. This does not work when code or a
{@link android.R.styleable} link is encountered in the first sentence.

Switch to checking for whitespace characters after the '.' character.

Bug: 62900335
Test: make aapt2_tests
Change-Id: I8238f6a6304c9c2f92e2e576ca8962a59c2b20ea
diff --git a/tools/aapt2/java/JavaClassGenerator.cpp b/tools/aapt2/java/JavaClassGenerator.cpp
index 2a23aa9..44fa0f1 100644
--- a/tools/aapt2/java/JavaClassGenerator.cpp
+++ b/tools/aapt2/java/JavaClassGenerator.cpp
@@ -299,24 +299,16 @@
       }
 
       const ResourceName& attr_name = entry.attr_ref->name.value();
-      styleable_comment << "<tr><td>";
-      styleable_comment << "<code>{@link #" << entry.field_name << " "
-                        << (!attr_name.package.empty()
-                                ? attr_name.package
-                                : context_->GetCompilationPackage())
-                        << ":" << attr_name.entry << "}</code>";
-      styleable_comment << "</td>";
-
-      styleable_comment << "<td>";
+      styleable_comment << "<tr><td><code>{@link #" << entry.field_name << " "
+                        << (!attr_name.package.empty() ? attr_name.package
+                                                       : context_->GetCompilationPackage())
+                        << ":" << attr_name.entry << "}</code></td>";
 
       // Only use the comment up until the first '.'. This is to stay compatible with
       // the way old AAPT did it (presumably to keep it short and to avoid including
       // annotations like @hide which would affect this Styleable).
-      auto iter = std::find(attr_comment_line.begin(), attr_comment_line.end(), '.');
-      if (iter != attr_comment_line.end()) {
-        attr_comment_line = attr_comment_line.substr(0, (iter - attr_comment_line.begin()) + 1);
-      }
-      styleable_comment << attr_comment_line << "</td></tr>\n";
+      styleable_comment << "<td>" << AnnotationProcessor::ExtractFirstSentence(attr_comment_line)
+                        << "</td></tr>\n";
     }
     styleable_comment << "</table>\n";