Introduce PatternRules Refaster rule collection

See google/guava#6483.

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/PatternRules.java

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+package tech.picnic.errorprone.refasterrules;
+
+import com.google.common.base.Predicates;
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import java.util.function.Predicate;
+import java.util.regex.Pattern;
+import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+
+/** Refaster rules related to code dealing with regular expressions. */
+@OnlineDocumentation
+final class PatternRules {
+  private PatternRules() {}
+
+  /** Prefer {@link Pattern#asPredicate()} over non-JDK alternatives. */
+  // XXX: This rule could also replace `s -> pattern.matcher(s).find()`, though the lambda
+  // expression may match functional interfaces other than `Predicate`. If we do add such a rule, we
+  // should also add a rule that replaces `s -> pattern.matcher(s).matches()` with
+  // `pattern.asMatchPredicate()`.
+  static final class PatternAsPredicate {
+    @BeforeTemplate
+    Predicate<CharSequence> before(Pattern pattern) {
+      return Predicates.contains(pattern);
+    }
+
+    @AfterTemplate
+    Predicate<String> after(Pattern pattern) {
+      return pattern.asPredicate();
+    }
+  }
+
+  /** Prefer {@link Pattern#asPredicate()} over non-JDK alternatives. */
+  static final class PatternCompileAsPredicate {
+    @BeforeTemplate
+    Predicate<CharSequence> before(String pattern) {
+      return Predicates.containsPattern(pattern);
+    }
+
+    @AfterTemplate
+    Predicate<String> after(String pattern) {
+      return Pattern.compile(pattern).asPredicate();
+    }
+  }
+}

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/PatternRulesTestInput.java

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+package tech.picnic.errorprone.refasterrules;
+
+import com.google.common.base.Predicates;
+import com.google.common.collect.ImmutableSet;
+import java.util.function.Predicate;
+import java.util.regex.Pattern;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class PatternRulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<Object> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(Predicates.class);
+  }
+
+  Predicate<?> testPatternAsPredicate() {
+    return Predicates.contains(Pattern.compile("foo"));
+  }
+
+  Predicate<?> testPatternCompileAsPredicate() {
+    return Predicates.containsPattern("foo");
+  }
+}

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/PatternRulesTestOutput.java

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+package tech.picnic.errorprone.refasterrules;
+
+import com.google.common.base.Predicates;
+import com.google.common.collect.ImmutableSet;
+import java.util.function.Predicate;
+import java.util.regex.Pattern;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class PatternRulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<Object> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(Predicates.class);
+  }
+
+  Predicate<?> testPatternAsPredicate() {
+    return Pattern.compile("foo").asPredicate();
+  }
+
+  Predicate<?> testPatternCompileAsPredicate() {
+    return Pattern.compile("foo").asPredicate();
+  }
+}