diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index b4924602af..9ca1a67369 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -5,8 +5,6 @@ on:
   push:
     branches: [ master ]
   pull_request:
-    branches: [ master ]
-
 
 jobs:
   build-and-test:
diff --git a/src/main/java/com/amazon/ion/_private/SuppressFBWarnings.kt b/src/main/java/com/amazon/ion/_private/SuppressFBWarnings.kt
new file mode 100644
index 0000000000..8cb0e2240f
--- /dev/null
+++ b/src/main/java/com/amazon/ion/_private/SuppressFBWarnings.kt
@@ -0,0 +1,18 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+package com.amazon.ion._private
+
+/**
+ * SpotBugs looks for an annotation called `SuppressFBWarnings` regardless of the package it is in.
+ * This will allow us to disable some SpotBugs rules when we want e.g. to allow switch case fallthrough.
+ *
+ * We are implementing our own annotation so that we don't have to declare any dependency on another package just for this.
+ */
+annotation class SuppressFBWarnings(
+    /**
+     * The set of FindBugs/SpotBugs warnings that are to be suppressed in the annotated element.
+     * The value can be a bug category, kind, or pattern.
+     * For examples of some bug types, see https://spotbugs.readthedocs.io/en/stable/bugDescriptions.html
+     */
+    vararg val value: String = []
+)
diff --git a/src/main/java/com/amazon/ion/impl/IonReaderContinuableCoreBinary.java b/src/main/java/com/amazon/ion/impl/IonReaderContinuableCoreBinary.java
index 46eb840208..9ab67d9948 100644
--- a/src/main/java/com/amazon/ion/impl/IonReaderContinuableCoreBinary.java
+++ b/src/main/java/com/amazon/ion/impl/IonReaderContinuableCoreBinary.java
@@ -9,6 +9,7 @@
 import com.amazon.ion.IonException;
 import com.amazon.ion.IonType;
 import com.amazon.ion.Timestamp;
+import com.amazon.ion._private.SuppressFBWarnings;
 import com.amazon.ion.impl.bin.IntList;
 import com.amazon.ion.impl.bin.utf8.Utf8StringDecoder;
 import com.amazon.ion.impl.bin.utf8.Utf8StringDecoderPool;
@@ -672,6 +673,7 @@ private BigDecimal readTimestampFraction_1_1() {
      * Reads an Ion 1.1 long form timestamp.
      * @return the value.
      */
+    @SuppressFBWarnings("SF_SWITCH_FALLTHROUGH")
     private Timestamp readTimestampLongForm_1_1() {
         int year;
         int month = 1;
@@ -739,6 +741,7 @@ private Timestamp readTimestampLongForm_1_1() {
      * Reads an Ion 1.1 timestamp in either the long or short form.
      * @return the value.
      */
+    @SuppressFBWarnings("SF_SWITCH_FALLTHROUGH")
     private Timestamp readTimestamp_1_1() {
         if (valueTid.variableLength) {
             return readTimestampLongForm_1_1();
diff --git a/src/main/java/com/amazon/ion/impl/IonTypeID.java b/src/main/java/com/amazon/ion/impl/IonTypeID.java
index 5aa05799b1..f7a0c6f7d7 100644
--- a/src/main/java/com/amazon/ion/impl/IonTypeID.java
+++ b/src/main/java/com/amazon/ion/impl/IonTypeID.java
@@ -352,6 +352,8 @@ private IonTypeID(byte id, int minorVersion) {
                             case TIMESTAMP_NANOS_PRECISION_WITH_OFFSET:
                                 length = 9;
                                 break;
+                            default:
+                                // Unreachable
                         }
                     } else {
                         length = lowerNibble;
diff --git a/src/main/java/com/amazon/ion/impl/_Private_IonConstants.java b/src/main/java/com/amazon/ion/impl/_Private_IonConstants.java
index bde35c56a0..e925616306 100644
--- a/src/main/java/com/amazon/ion/impl/_Private_IonConstants.java
+++ b/src/main/java/com/amazon/ion/impl/_Private_IonConstants.java
@@ -16,6 +16,7 @@
 package com.amazon.ion.impl;
 
 import com.amazon.ion.IonException;
+import com.amazon.ion._private.SuppressFBWarnings;
 
 /**
  * NOT FOR APPLICATION USE!
@@ -108,6 +109,7 @@ public static final boolean isSurrogate(int c) {
     /**
      * The byte sequence indicating use of Ion 1.0 binary format.
      */
+    @SuppressFBWarnings("MS_MUTABLE_ARRAY")
     public static final byte[] BINARY_VERSION_MARKER_1_0 = { (byte) 0xE0,
                                                              (byte) 0x01,
                                                              (byte) 0x00,
@@ -116,6 +118,7 @@ public static final boolean isSurrogate(int c) {
     /**
      * The byte sequence indicating use of Ion 1.1 binary format.
      */
+    @SuppressFBWarnings("MS_MUTABLE_ARRAY")
     public static final byte[] BINARY_VERSION_MARKER_1_1 = { (byte) 0xE0,
                                                              (byte) 0x01,
                                                              (byte) 0x01,
diff --git a/src/main/java/com/amazon/ion/impl/bin/Ion_1_1_Constants.java b/src/main/java/com/amazon/ion/impl/bin/Ion_1_1_Constants.java
index b1924b7bd2..7aa507e8ae 100644
--- a/src/main/java/com/amazon/ion/impl/bin/Ion_1_1_Constants.java
+++ b/src/main/java/com/amazon/ion/impl/bin/Ion_1_1_Constants.java
@@ -3,6 +3,7 @@
 package com.amazon.ion.impl.bin;
 
 import com.amazon.ion.Timestamp;
+import com.amazon.ion._private.SuppressFBWarnings;
 
 /**
  * Contains constants (other than OpCodes) which are generally applicable to both reading and writing binary Ion 1.1
@@ -63,7 +64,7 @@ private Ion_1_1_Constants() {}
     public static final int L_TIMESTAMP_OFFSET_BIAS = 1440; // 24 hours * 60 min/hour
 
     //////// Lookup tables ////////
-
+    @SuppressFBWarnings("MS_MUTABLE_ARRAY")
     public static final Timestamp.Precision[] S_TIMESTAMP_PRECISION_FOR_TYPE_ID_OFFSET = new Timestamp.Precision[] {
         Timestamp.Precision.YEAR, // 0x70
         Timestamp.Precision.MONTH, // 0x71
@@ -80,6 +81,7 @@ private Ion_1_1_Constants() {}
         Timestamp.Precision.SECOND, // 0x7C (nanosecond offset)
     };
 
+    @SuppressFBWarnings("MS_MUTABLE_ARRAY")
     public static final Timestamp.Precision[] L_TIMESTAMP_PRECISION_FOR_LENGTH = new Timestamp.Precision[] {
         null, // Length 0: illegal
         null, // Length 1: illegal