Simplify if statements

See gh-17884

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/src/main/java/org/springframework/boot/autoconfigureprocessor/Elements.java

@@ -49,7 +49,7 @@ final class Elements {
 		if (type instanceof DeclaredType) {
 			DeclaredType declaredType = (DeclaredType) type;
 			Element enclosingElement = declaredType.asElement().getEnclosingElement();
-			if (enclosingElement != null && enclosingElement instanceof TypeElement) {
+			if (enclosingElement instanceof TypeElement) {
 				return (TypeElement) enclosingElement;
 			}
 		}

spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/util/SystemPropertyUtils.java

@@ -109,7 +109,7 @@ public abstract class SystemPropertyUtils {
 				placeholder = parseStringValue(properties, value, placeholder, visitedPlaceholders);
 				// Now obtain the value for the fully resolved key...
 				String propVal = resolvePlaceholder(properties, value, placeholder);
-				if (propVal == null && VALUE_SEPARATOR != null) {
+				if (propVal == null) {
 					int separatorIndex = placeholder.indexOf(VALUE_SEPARATOR);
 					if (separatorIndex != -1) {
 						String actualPlaceholder = placeholder.substring(0, separatorIndex);

spring-boot-project/spring-boot-tools/spring-boot-test-support/src/main/java/org/springframework/boot/testsupport/system/OutputCapture.java

@@ -59,7 +59,7 @@ class OutputCapture implements CapturedOutput {
 		if (obj == this) {
 			return true;
 		}
-		if (obj instanceof CapturedOutput || obj instanceof CharSequence) {
+		if (obj instanceof CharSequence) {
 			return getAll().equals(obj.toString());
 		}
 		return false;