Fix spelling in comments: heirarchy → hierarchy

core/src/main/java/org/bitcoinj/crypto/DeterministicHierarchy.java

@@ -58,7 +58,7 @@ public class DeterministicHierarchy {
     }
 
     /**
-     * Inserts a key into the heirarchy. Used during deserialization: you normally don't need this. Keys must be
+     * Inserts a key into the hierarchy. Used during deserialization: you normally don't need this. Keys must be
      * inserted in order.
      */
     public final void putKey(DeterministicKey key) {

core/src/main/java/org/bitcoinj/crypto/DeterministicKey.java

@@ -355,13 +355,13 @@ public class DeterministicKey extends ECKey {
     public ECDSASignature sign(Sha256Hash input, @Nullable KeyParameter aesKey) throws KeyCrypterException {
         if (isEncrypted()) {
             // If the key is encrypted, ECKey.sign will decrypt it first before rerunning sign. Decryption walks the
-            // key heirarchy to find the private key (see below), so, we can just run the inherited method.
+            // key hierarchy to find the private key (see below), so, we can just run the inherited method.
             return super.sign(input, aesKey);
         } else {
             // If it's not encrypted, derive the private via the parents.
             final BigInteger privateKey = findOrDerivePrivateKey();
             if (privateKey == null) {
-                // This key is a part of a public-key only heirarchy and cannot be used for signing
+                // This key is a part of a public-key only hierarchy and cannot be used for signing
                 throw new MissingPrivateKeyException();
             }
             return super.doSign(input, privateKey);
@@ -583,7 +583,7 @@ public class DeterministicKey extends ECKey {
     }
 
     /**
-     * Verifies equality of all fields but NOT the parent pointer (thus the same key derived in two separate heirarchy
+     * Verifies equality of all fields but NOT the parent pointer (thus the same key derived in two separate hierarchy
      * objects will equal each other.
      */
     @Override

core/src/main/java/org/bitcoinj/wallet/DeterministicKeyChain.java

@@ -894,7 +894,7 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
                 if (!isWatchingAccountKey) {
                     // If the non-encrypted case, the non-leaf keys (account, internal, external) have already
                     // been rederived and inserted at this point. In the encrypted case though,
-                    // we can't rederive and we must reinsert, potentially building the heirarchy object
+                    // we can't rederive and we must reinsert, potentially building the hierarchy object
                     // if need be.
                     if (path.size() == 0) {
                         // Master key.

core/src/test/java/org/bitcoinj/crypto/ChildKeyDerivationTest.java

@@ -136,7 +136,7 @@ public class ChildKeyDerivationTest {
 
     @Test
     public void encryptedDerivation() throws Exception {
-        // Check that encrypting a parent key in the heirarchy and then deriving from it yields a DeterministicKey
+        // Check that encrypting a parent key in the hierarchy and then deriving from it yields a DeterministicKey
         // with no private key component, and that the private key bytes are derived on demand.
         KeyCrypter scrypter = new KeyCrypterScrypt();
         KeyParameter aesKey = scrypter.deriveKey("we never went to the moon");