diff --git a/java/ql/src/semmle/code/java/frameworks/guava/Base.qll b/java/ql/src/semmle/code/java/frameworks/guava/Base.qll
index 01e90e7b0a7..174d8d19f33 100644
--- a/java/ql/src/semmle/code/java/frameworks/guava/Base.qll
+++ b/java/ql/src/semmle/code/java/frameworks/guava/Base.qll
@@ -50,7 +50,7 @@ private class GuavaBaseCsv extends SummaryModelCsv {
         "com.google.common.base;Ascii;false;toUpperCase;(String);;Argument[0];ReturnValue;taint",
         "com.google.common.base;Ascii;false;truncate;(CharSequence,int,String);;Argument[0];ReturnValue;taint",
         "com.google.common.base;Ascii;false;truncate;(CharSequence,int,String);;Argument[2];ReturnValue;taint",
-        "com.google.common.base;CaseFormat;true;to;(CharFormat,String);;Argument[1];ReturnValue;taint",
+        "com.google.common.base;CaseFormat;true;to;(CaseFormat,String);;Argument[1];ReturnValue;taint",
         "com.google.common.base;Converter;true;apply;;;Argument[0];ReturnValue;taint",
         "com.google.common.base;Converter;true;convert;;;Argument[0];ReturnValue;taint",
         "com.google.common.base;Converter;true;convertAll;;;Argument[0];ReturnValue;taint",
@@ -65,6 +65,8 @@ private class GuavaBaseCsv extends SummaryModelCsv {
         "com.google.common.base;Optional;true;asSet;();;Argument[-1];ReturnValue;taint",
         "com.google.common.base;Optional;true;of;(T);;Argument[0];ReturnValue;taint",
         "com.google.common.base;Optional;true;or;;;Argument[-1];ReturnValue;taint",
+        "com.google.common.base;Optional;true;or;;;Argument[0];ReturnValue;taint",
+        "com.google.common.base;Optional;true;orNull;();;Argument[-1];ReturnValue;taint",
         "com.google.common.base;Optional;true;presentInstances;;;Argument[0];ReturnValue;taint",
         "com.google.common.base;Optional;true;toJavaUtil;();;Argument[-1];ReturnValue;taint",
         "com.google.common.base;Optional;true;toJavaUtil;(Optional<T>);;Argument[0];ReturnValue;taint",
diff --git a/java/ql/test/library-tests/frameworks/guava/TestBase.java b/java/ql/test/library-tests/frameworks/guava/TestBase.java
index 8da63965d58..c91bd06c4f8 100644
--- a/java/ql/test/library-tests/frameworks/guava/TestBase.java
+++ b/java/ql/test/library-tests/frameworks/guava/TestBase.java
@@ -2,6 +2,7 @@ package com.google.common.base;
 
 import java.util.Map;
 import java.util.HashMap;
+import java.util.concurrent.TimeUnit;
 
 class TestBase {
     String taint() { return "tainted"; }
@@ -59,6 +60,50 @@ class TestBase {
 
     void test4() {
         sink(Preconditions.checkNotNull(taint())); // $numTaintFlow=1
+        sink(Verify.verifyNotNull(taint())); // $numTaintFlow=1
+    }
+
+    void test5() {
+        sink(Ascii.toLowerCase(taint())); // $numTaintFlow=1
+        sink(Ascii.toUpperCase(taint())); // $numTaintFlow=1
+        sink(Ascii.truncate(taint(), 3, "...")); // $numTaintFlow=1
+        sink(Ascii.truncate("abcabcabc", 3, taint())); // $numTaintFlow=1
+        sink(CaseFormat.LOWER_CAMEL.to(CaseFormat.UPPER_UNDERSCORE, taint())); // $numTaintFlow=1
+        sink(CaseFormat.LOWER_HYPHEN.converterTo(CaseFormat.UPPER_CAMEL).convert(taint())); // $numTaintFlow=1
+        sink(CaseFormat.LOWER_UNDERSCORE.converterTo(CaseFormat.LOWER_HYPHEN).reverse().convert(taint())); // $numTaintFlow=1
+    }
+
+    void test6() {
+        sink(Suppliers.memoize(Suppliers.memoizeWithExpiration(Suppliers.synchronizedSupplier(Suppliers.ofInstance(taint())), 3, TimeUnit.HOURS))); // $numTaintFlow=1
+    }
+
+    void test7() {
+        sink(MoreObjects.firstNonNull(taint(), "abc")); // $numTaintFlow=1
+        sink(MoreObjects.firstNonNull(null, taint())); // $numTaintFlow=1
+        sink(MoreObjects.toStringHelper(taint()).add("x", 3).omitNullValues().toString()); // $numTaintFlow=1
+        sink(MoreObjects.toStringHelper((Object) taint()).toString());
+        sink(MoreObjects.toStringHelper("a").add("x", 3).add(taint(), 4).toString()); // $numTaintFlow=1
+        sink(MoreObjects.toStringHelper("a").add("x", taint()).toString()); // $numTaintFlow=1
+        sink(MoreObjects.toStringHelper("a").addValue(taint()).toString()); // $numTaintFlow=1
+        MoreObjects.ToStringHelper h = MoreObjects.toStringHelper("a");
+        h.add("x", 3).add(taint(), 4);
+        sink(h.add("z",5).toString()); // $numTaintFlow=1
+    }
+
+    void test8() {
+        Optional<String> x = Optional.of(taint());
+        sink(x); // $numTaintFlow=1
+        sink(x.get()); // $numTaintFlow=1
+        sink(x.or("hi")); // $numTaintFlow=1
+        sink(x.orNull()); // $numTaintFlow=1
+        sink(x.asSet()); // $numTaintFlow=1
+        sink(Optional.fromJavaUtil(x.toJavaUtil())); // $numTaintFlow=1
+        sink(Optional.fromJavaUtil(Optional.toJavaUtil(x))); // $numTaintFlow=1
+        sink(x.asSet()); // $numTaintFlow=1
+        sink(Optional.fromNullable(taint())); // $numTaintFlow=1
+        sink(Optional.absent().or(x)); // $numTaintFlow=1
+        sink(Optional.absent().or(taint())); // $numTaintFlow=1
+        sink(Optional.presentInstances(Optional.of(x).asSet())); // $numTaintFlow=1
     }
 
     void test5() {
diff --git a/java/ql/test/stubs/guava-30.0/com/google/common/base/Ascii.java b/java/ql/test/stubs/guava-30.0/com/google/common/base/Ascii.java
new file mode 100644
index 00000000000..f5feafe474f
--- /dev/null
+++ b/java/ql/test/stubs/guava-30.0/com/google/common/base/Ascii.java
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2010 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.base;
+
+public final class Ascii {
+  public static String toLowerCase(String string) {
+    return null;
+  }
+
+  public static String toLowerCase(CharSequence chars) {
+    return null;
+  }
+
+  public static char toLowerCase(char c) {
+    return '0';
+  }
+
+  public static String toUpperCase(String string) {
+    return null;
+  }
+
+  public static String toUpperCase(CharSequence chars) {
+    return null;
+  }
+
+  public static char toUpperCase(char c) {
+    return '0';
+  }
+
+  public static boolean isLowerCase(char c) {
+    return false;
+  }
+
+  public static boolean isUpperCase(char c) {
+    return false;
+  }
+
+  public static String truncate(CharSequence seq, int maxLength, String truncationIndicator) {
+    return null;
+  }
+
+  public static boolean equalsIgnoreCase(CharSequence s1, CharSequence s2) {
+    return false;
+  }
+
+}
diff --git a/java/ql/test/stubs/guava-30.0/com/google/common/base/CaseFormat.java b/java/ql/test/stubs/guava-30.0/com/google/common/base/CaseFormat.java
new file mode 100644
index 00000000000..4d0df360197
--- /dev/null
+++ b/java/ql/test/stubs/guava-30.0/com/google/common/base/CaseFormat.java
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2006 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.base;
+
+public enum CaseFormat {
+  LOWER_HYPHEN,
+  LOWER_UNDERSCORE,
+  LOWER_CAMEL,
+  UPPER_CAMEL,
+  UPPER_UNDERSCORE;
+
+  public final String to(CaseFormat format, String str) {
+    return null;
+  }
+
+  public Converter<String, String> converterTo(CaseFormat targetFormat) {
+    return null;
+  }
+
+}
diff --git a/java/ql/test/stubs/guava-30.0/com/google/common/base/Converter.java b/java/ql/test/stubs/guava-30.0/com/google/common/base/Converter.java
new file mode 100644
index 00000000000..d4e59f3ff91
--- /dev/null
+++ b/java/ql/test/stubs/guava-30.0/com/google/common/base/Converter.java
@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2008 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.base;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public abstract class Converter<A, B> implements Function<A, B> {
+  public final @Nullable B convert(@Nullable A a) {
+    return null;
+  }
+
+  public Iterable<B> convertAll(final Iterable<? extends A> fromIterable) {
+    return null;
+  }
+
+  public Converter<B, A> reverse() {
+    return null;
+  }
+
+  public final <C> Converter<A, C> andThen(Converter<B, C> secondConverter) {
+    return null;
+  }
+
+  @Override
+  public final @Nullable B apply(@Nullable A a) {
+    return null;
+  }
+
+  @Override
+  public boolean equals(@Nullable Object object) {
+    return false;
+  }
+
+  public static <A, B> Converter<A, B> from(
+      Function<? super A, ? extends B> forwardFunction,
+      Function<? super B, ? extends A> backwardFunction) {
+    return null;
+  }
+
+  public static <T> Converter<T, T> identity() {
+    return null;
+  }
+
+}
diff --git a/java/ql/test/stubs/guava-30.0/com/google/common/base/MoreObjects.java b/java/ql/test/stubs/guava-30.0/com/google/common/base/MoreObjects.java
index 3f4912b021b..31e3638adec 100644
--- a/java/ql/test/stubs/guava-30.0/com/google/common/base/MoreObjects.java
+++ b/java/ql/test/stubs/guava-30.0/com/google/common/base/MoreObjects.java
@@ -1,9 +1,102 @@
-package com.google.common.base;
+/*
+ * Copyright (C) 2014 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
 
+package com.google.common.base;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public final class MoreObjects {
-    public static <T> T firstNonNull(@Nullable T first, @Nullable T second) {
-        return null;
+  public static <T> T firstNonNull(@Nullable T first, @Nullable T second) {
+    return null;
+  }
+
+  public static ToStringHelper toStringHelper(Object self) {
+    return null;
+  }
+
+  public static ToStringHelper toStringHelper(Class<?> clazz) {
+    return null;
+  }
+
+  public static ToStringHelper toStringHelper(String className) {
+    return null;
+  }
+
+  public static final class ToStringHelper {
+    public ToStringHelper omitNullValues() {
+      return null;
     }
-}
\ No newline at end of file
+
+    public ToStringHelper add(String name, @Nullable Object value) {
+      return null;
+    }
+
+    public ToStringHelper add(String name, boolean value) {
+      return null;
+    }
+
+    public ToStringHelper add(String name, char value) {
+      return null;
+    }
+
+    public ToStringHelper add(String name, double value) {
+      return null;
+    }
+
+    public ToStringHelper add(String name, float value) {
+      return null;
+    }
+
+    public ToStringHelper add(String name, int value) {
+      return null;
+    }
+
+    public ToStringHelper add(String name, long value) {
+      return null;
+    }
+
+    public ToStringHelper addValue(@Nullable Object value) {
+      return null;
+    }
+
+    public ToStringHelper addValue(boolean value) {
+      return null;
+    }
+
+    public ToStringHelper addValue(char value) {
+      return null;
+    }
+
+    public ToStringHelper addValue(double value) {
+      return null;
+    }
+
+    public ToStringHelper addValue(float value) {
+      return null;
+    }
+
+    public ToStringHelper addValue(int value) {
+      return null;
+    }
+
+    public ToStringHelper addValue(long value) {
+      return null;
+    }
+
+    @Override
+    public String toString() {
+      return null;
+    }
+
+  }
+}
diff --git a/java/ql/test/stubs/guava-30.0/com/google/common/base/Optional.java b/java/ql/test/stubs/guava-30.0/com/google/common/base/Optional.java
index f6f757ac994..3f39995651a 100644
--- a/java/ql/test/stubs/guava-30.0/com/google/common/base/Optional.java
+++ b/java/ql/test/stubs/guava-30.0/com/google/common/base/Optional.java
@@ -31,11 +31,11 @@ public abstract class Optional<T> implements Serializable {
   }
 
   public static <T> @Nullable Optional<T> fromJavaUtil(
-      java.util.Optional<T> javaUtilOptional) {
+      java.util.@Nullable Optional<T> javaUtilOptional) {
     return null;
   }
 
-  public static <T> java.util.Optional<T> toJavaUtil(
+  public static <T> java.util.@Nullable Optional<T> toJavaUtil(
       @Nullable Optional<T> googleOptional) {
     return null;
   }
diff --git a/java/ql/test/stubs/guava-30.0/com/google/common/base/Suppliers.java b/java/ql/test/stubs/guava-30.0/com/google/common/base/Suppliers.java
new file mode 100644
index 00000000000..5e5b2d47820
--- /dev/null
+++ b/java/ql/test/stubs/guava-30.0/com/google/common/base/Suppliers.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2007 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.base;
+import java.util.concurrent.TimeUnit;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public final class Suppliers {
+  public static <F, T> Supplier<T> compose(Function<? super F, T> function, Supplier<F> supplier) {
+    return null;
+  }
+
+  public static <T> Supplier<T> memoize(Supplier<T> delegate) {
+    return null;
+  }
+
+  public static <T> Supplier<T> memoizeWithExpiration(
+      Supplier<T> delegate, long duration, TimeUnit unit) {
+    return null;
+  }
+
+  public static <T> Supplier<T> ofInstance(@Nullable T instance) {
+    return null;
+  }
+
+  public static <T> Supplier<T> synchronizedSupplier(Supplier<T> delegate) {
+    return null;
+  }
+
+  public static <T> Function<Supplier<T>, T> supplierFunction() {
+    return null;
+  }
+
+}
diff --git a/java/ql/test/stubs/guava-30.0/com/google/common/base/Verify.java b/java/ql/test/stubs/guava-30.0/com/google/common/base/Verify.java
new file mode 100644
index 00000000000..8016ec83489
--- /dev/null
+++ b/java/ql/test/stubs/guava-30.0/com/google/common/base/Verify.java
@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2013 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.base;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public final class Verify {
+  public static void verify(boolean expression) {
+  }
+
+  public static void verify(
+      boolean expression,
+      @Nullable String errorMessageTemplate,
+      @Nullable Object @Nullable ... errorMessageArgs) {
+  }
+
+  public static void verify(boolean expression, @Nullable String errorMessageTemplate, char p1) {
+  }
+
+  public static void verify(boolean expression, @Nullable String errorMessageTemplate, int p1) {
+  }
+
+  public static void verify(boolean expression, @Nullable String errorMessageTemplate, long p1) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, @Nullable Object p1) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, char p1, char p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, int p1, char p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, long p1, char p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, @Nullable Object p1, char p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, char p1, int p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, int p1, int p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, long p1, int p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, @Nullable Object p1, int p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, char p1, long p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, int p1, long p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, long p1, long p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, @Nullable Object p1, long p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, char p1, @Nullable Object p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, int p1, @Nullable Object p2) {
+  }
+
+  public static void verify(
+      boolean expression, @Nullable String errorMessageTemplate, long p1, @Nullable Object p2) {
+  }
+
+  public static void verify(
+      boolean expression,
+      @Nullable String errorMessageTemplate,
+      @Nullable Object p1,
+      @Nullable Object p2) {
+  }
+
+  public static void verify(
+      boolean expression,
+      @Nullable String errorMessageTemplate,
+      @Nullable Object p1,
+      @Nullable Object p2,
+      @Nullable Object p3) {
+  }
+
+  public static void verify(
+      boolean expression,
+      @Nullable String errorMessageTemplate,
+      @Nullable Object p1,
+      @Nullable Object p2,
+      @Nullable Object p3,
+      @Nullable Object p4) {
+  }
+
+  public static <T> T verifyNotNull(@Nullable T reference) {
+    return null;
+  }
+
+  public static <T> T verifyNotNull(
+      @Nullable T reference,
+      @Nullable String errorMessageTemplate,
+      @Nullable Object @Nullable ... errorMessageArgs) {
+    return null;
+  }
+
+}