Allow empty certificate and lookup defintions

Author: mlookaxw

src/main/java/com/axway/yamles/utils/merge/certs/CertificatesConfig.java

@@ -46,7 +46,7 @@ public static CertificatesConfig loadConfig(String yaml) {
 
 	@JsonCreator
 	public CertificatesConfig(@JsonProperty("certificates") Map<String, Alias> aliases) {
-		this.aliases = Objects.requireNonNull(aliases, "no aliases defined");
+		this.aliases = (aliases != null) ? aliases : Collections.emptyMap();
 		this.aliases.forEach((k, v) -> {
 			v.setName(k);
 		});

src/main/java/com/axway/yamles/utils/spi/LookupFunctionConfig.java

@@ -44,7 +44,7 @@ public static LookupFunctionConfig fromJSON(String json) {
 
 	@JsonCreator
 	protected LookupFunctionConfig(@JsonProperty("lookups") Map<String, LookupSource> sources) {
-		this.sources = Objects.requireNonNull(sources, "no sources defined");
+		this.sources = (sources != null) ? sources : Collections.emptyMap();
 		this.sources.forEach((k, v) -> {
 			v.setAlias(k);
 		});

src/test/java/com/axway/yamles/utils/merge/certs/CertificatesConfigTest.java

@@ -18,20 +18,29 @@ void test() {
 				+ "      key: key.pem\n" //
 				+ "      pass: changeme\n" //
 				+ "...";
-		
+
 		CertificatesConfig cc = CertificatesConfig.loadConfig(yaml);
 		assertNotNull(cc.getAliases());
 		assertNotNull(cc.getAliases().get("alias"));
-		
+
 		Alias a = cc.getAliases().get("alias");
 		assertEquals("alias", a.getName());
-		assertEquals("string", a.getConfigSource().getName());		
+		assertEquals("string", a.getConfigSource().getName());
 		assertEquals("file", a.getProvider());
 		assertNotNull(a.getConfig());
-		
+
 		assertEquals("cert.pem", a.getConfig().get("cert"));
 		assertEquals("key.pem", a.getConfig().get("key"));
 		assertEquals("changeme", a.getConfig().get("pass"));
 	}
 
+	@Test
+	void empty_certificate_config() {
+		String yaml = "---\n" //
+				+ "certificates:";
+
+		CertificatesConfig cc = CertificatesConfig.loadConfig(yaml);
+		assertNotNull(cc.getAliases());
+		assertEquals(0, cc.getAliases().size());
+	}
 }